diff --git a/Cargo.lock b/Cargo.lock
index 2b68136b5..6efffd62e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -665,6 +665,7 @@ dependencies = [
  "tokio",
  "tokio-stream",
  "tree_hash",
+ "tree_hash_derive",
  "types",
  "unused_port",
 ]
@@ -2343,6 +2344,8 @@ dependencies = [
  "libsecp256k1",
  "lighthouse_network",
  "mediatype",
+ "mime",
+ "pretty_reqwest_error",
  "procinfo",
  "proto_array",
  "psutil",
@@ -2353,6 +2356,7 @@ dependencies = [
  "serde_json",
  "slashing_protection",
  "store",
+ "tokio",
  "types",
 ]
 
@@ -2795,6 +2799,7 @@ dependencies = [
  "lru 0.7.8",
  "mev-rs",
  "parking_lot 0.12.1",
+ "pretty_reqwest_error",
  "rand 0.8.5",
  "reqwest",
  "sensitive_url",
@@ -6275,6 +6280,14 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "pretty_reqwest_error"
+version = "0.1.0"
+dependencies = [
+ "reqwest",
+ "sensitive_url",
+]
+
 [[package]]
 name = "prettyplease"
 version = "0.1.25"
@@ -7925,7 +7938,8 @@ dependencies = [
 [[package]]
 name = "ssz_types"
 version = "0.5.3"
-source = "git+https://github.com/sigp/ssz_types?rev=63a80d04286c8561d5c211230a21bf1299d66059#63a80d04286c8561d5c211230a21bf1299d66059"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e43767964a80b2fdeda7a79a57a2b6cbca966688d5b81da8fe91140a94f552a1"
 dependencies = [
  "arbitrary",
  "derivative",
diff --git a/Cargo.toml b/Cargo.toml
index 092ccf32f..bd2561351 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -35,6 +35,7 @@ members = [
     "common/lru_cache",
     "common/malloc_utils",
     "common/oneshot_broadcast",
+    "common/pretty_reqwest_error",
     "common/sensitive_url",
     "common/slot_clock",
     "common/system_health",
diff --git a/beacon_node/beacon_chain/Cargo.toml b/beacon_node/beacon_chain/Cargo.toml
index 504f4114a..e00b44301 100644
--- a/beacon_node/beacon_chain/Cargo.toml
+++ b/beacon_node/beacon_chain/Cargo.toml
@@ -35,9 +35,10 @@ sloggers = { version = "2.1.1", features = ["json"] }
 slot_clock = { path = "../../common/slot_clock" }
 ethereum_hashing = "1.0.0-beta.2"
 ethereum_ssz = "0.5.0"
-ssz_types = "0.5.0"
+ssz_types = "0.5.3"
 ethereum_ssz_derive = "0.5.0"
 state_processing = { path = "../../consensus/state_processing" }
+tree_hash_derive = "0.5.0"
 tree_hash = "0.5.0"
 types = { path = "../../consensus/types" }
 tokio = "1.14.0"
diff --git a/beacon_node/beacon_chain/src/attestation_verification.rs b/beacon_node/beacon_chain/src/attestation_verification.rs
index 04f601fad..6df0758b2 100644
--- a/beacon_node/beacon_chain/src/attestation_verification.rs
+++ b/beacon_node/beacon_chain/src/attestation_verification.rs
@@ -117,14 +117,14 @@ pub enum Error {
     ///
     /// The peer has sent an invalid message.
     AggregatorPubkeyUnknown(u64),
-    /// The attestation has been seen before; either in a block, on the gossip network or from a
-    /// local validator.
+    /// The attestation or a superset of this attestation's aggregations bits for the same data
+    /// has been seen before; either in a block, on the gossip network or from a local validator.
     ///
     /// ## Peer scoring
     ///
     /// It's unclear if this attestation is valid, however we have already observed it and do not
     /// need to observe it again.
-    AttestationAlreadyKnown(Hash256),
+    AttestationSupersetKnown(Hash256),
     /// There has already been an aggregation observed for this validator, we refuse to process a
     /// second.
     ///
@@ -268,7 +268,7 @@ enum CheckAttestationSignature {
 struct IndexedAggregatedAttestation<'a, T: BeaconChainTypes> {
     signed_aggregate: &'a SignedAggregateAndProof<T::EthSpec>,
     indexed_attestation: IndexedAttestation<T::EthSpec>,
-    attestation_root: Hash256,
+    attestation_data_root: Hash256,
 }
 
 /// Wraps a `Attestation` that has been verified up until the point that an `IndexedAttestation` can
@@ -467,14 +467,17 @@ impl<'a, T: BeaconChainTypes> IndexedAggregatedAttestation<'a, T> {
         }
 
         // Ensure the valid aggregated attestation has not already been seen locally.
-        let attestation_root = attestation.tree_hash_root();
+        let attestation_data = &attestation.data;
+        let attestation_data_root = attestation_data.tree_hash_root();
+
         if chain
             .observed_attestations
             .write()
-            .is_known(attestation, attestation_root)
+            .is_known_subset(attestation, attestation_data_root)
             .map_err(|e| Error::BeaconChainError(e.into()))?
         {
-            return Err(Error::AttestationAlreadyKnown(attestation_root));
+            metrics::inc_counter(&metrics::AGGREGATED_ATTESTATION_SUBSETS);
+            return Err(Error::AttestationSupersetKnown(attestation_data_root));
         }
 
         let aggregator_index = signed_aggregate.message.aggregator_index;
@@ -520,7 +523,7 @@ impl<'a, T: BeaconChainTypes> IndexedAggregatedAttestation<'a, T> {
         if attestation.aggregation_bits.is_zero() {
             Err(Error::EmptyAggregationBitfield)
         } else {
-            Ok(attestation_root)
+            Ok(attestation_data_root)
         }
     }
 
@@ -533,7 +536,7 @@ impl<'a, T: BeaconChainTypes> IndexedAggregatedAttestation<'a, T> {
 
         let attestation = &signed_aggregate.message.aggregate;
         let aggregator_index = signed_aggregate.message.aggregator_index;
-        let attestation_root = match Self::verify_early_checks(signed_aggregate, chain) {
+        let attestation_data_root = match Self::verify_early_checks(signed_aggregate, chain) {
             Ok(root) => root,
             Err(e) => return Err(SignatureNotChecked(&signed_aggregate.message.aggregate, e)),
         };
@@ -568,7 +571,7 @@ impl<'a, T: BeaconChainTypes> IndexedAggregatedAttestation<'a, T> {
         Ok(IndexedAggregatedAttestation {
             signed_aggregate,
             indexed_attestation,
-            attestation_root,
+            attestation_data_root,
         })
     }
 }
@@ -577,7 +580,7 @@ impl<'a, T: BeaconChainTypes> VerifiedAggregatedAttestation<'a, T> {
     /// Run the checks that happen after the indexed attestation and signature have been checked.
     fn verify_late_checks(
         signed_aggregate: &SignedAggregateAndProof<T::EthSpec>,
-        attestation_root: Hash256,
+        attestation_data_root: Hash256,
         chain: &BeaconChain<T>,
     ) -> Result<(), Error> {
         let attestation = &signed_aggregate.message.aggregate;
@@ -587,13 +590,14 @@ impl<'a, T: BeaconChainTypes> VerifiedAggregatedAttestation<'a, T> {
         //
         // It's important to double check that the attestation is not already known, otherwise two
         // attestations processed at the same time could be published.
-        if let ObserveOutcome::AlreadyKnown = chain
+        if let ObserveOutcome::Subset = chain
             .observed_attestations
             .write()
-            .observe_item(attestation, Some(attestation_root))
+            .observe_item(attestation, Some(attestation_data_root))
             .map_err(|e| Error::BeaconChainError(e.into()))?
         {
-            return Err(Error::AttestationAlreadyKnown(attestation_root));
+            metrics::inc_counter(&metrics::AGGREGATED_ATTESTATION_SUBSETS);
+            return Err(Error::AttestationSupersetKnown(attestation_data_root));
         }
 
         // Observe the aggregator so we don't process another aggregate from them.
@@ -653,7 +657,7 @@ impl<'a, T: BeaconChainTypes> VerifiedAggregatedAttestation<'a, T> {
         let IndexedAggregatedAttestation {
             signed_aggregate,
             indexed_attestation,
-            attestation_root,
+            attestation_data_root,
         } = signed_aggregate;
 
         match check_signature {
@@ -677,7 +681,7 @@ impl<'a, T: BeaconChainTypes> VerifiedAggregatedAttestation<'a, T> {
             CheckAttestationSignature::No => (),
         };
 
-        if let Err(e) = Self::verify_late_checks(signed_aggregate, attestation_root, chain) {
+        if let Err(e) = Self::verify_late_checks(signed_aggregate, attestation_data_root, chain) {
             return Err(SignatureValid(indexed_attestation, e));
         }
 
diff --git a/beacon_node/beacon_chain/src/metrics.rs b/beacon_node/beacon_chain/src/metrics.rs
index 40f24af77..4dde5d36f 100644
--- a/beacon_node/beacon_chain/src/metrics.rs
+++ b/beacon_node/beacon_chain/src/metrics.rs
@@ -1016,6 +1016,17 @@ lazy_static! {
         "light_client_optimistic_update_verification_success_total",
         "Number of light client optimistic updates verified for gossip"
     );
+    /*
+    * Aggregate subset metrics
+     */
+    pub static ref SYNC_CONTRIBUTION_SUBSETS: Result<IntCounter> = try_create_int_counter(
+        "beacon_sync_contribution_subsets_total",
+        "Count of new sync contributions that are subsets of already known aggregates"
+    );
+    pub static ref AGGREGATED_ATTESTATION_SUBSETS: Result<IntCounter> = try_create_int_counter(
+        "beacon_aggregated_attestation_subsets_total",
+        "Count of new aggregated attestations that are subsets of already known aggregates"
+    );
 }
 
 /// Scrape the `beacon_chain` for metrics that are not constantly updated (e.g., the present slot,
diff --git a/beacon_node/beacon_chain/src/observed_aggregates.rs b/beacon_node/beacon_chain/src/observed_aggregates.rs
index bb0132f5f..18a761e29 100644
--- a/beacon_node/beacon_chain/src/observed_aggregates.rs
+++ b/beacon_node/beacon_chain/src/observed_aggregates.rs
@@ -1,7 +1,9 @@
 //! Provides an `ObservedAggregates` struct which allows us to reject aggregated attestations or
 //! sync committee contributions if we've already seen them.
 
-use std::collections::HashSet;
+use crate::sync_committee_verification::SyncCommitteeData;
+use ssz_types::{BitList, BitVector};
+use std::collections::HashMap;
 use std::marker::PhantomData;
 use tree_hash::TreeHash;
 use types::consts::altair::{
@@ -10,8 +12,16 @@ use types::consts::altair::{
 use types::slot_data::SlotData;
 use types::{Attestation, EthSpec, Hash256, Slot, SyncCommitteeContribution};
 
-pub type ObservedSyncContributions<E> = ObservedAggregates<SyncCommitteeContribution<E>, E>;
-pub type ObservedAggregateAttestations<E> = ObservedAggregates<Attestation<E>, E>;
+pub type ObservedSyncContributions<E> = ObservedAggregates<
+    SyncCommitteeContribution<E>,
+    E,
+    BitVector<<E as types::EthSpec>::SyncSubcommitteeSize>,
+>;
+pub type ObservedAggregateAttestations<E> = ObservedAggregates<
+    Attestation<E>,
+    E,
+    BitList<<E as types::EthSpec>::MaxValidatorsPerCommittee>,
+>;
 
 /// A trait use to associate capacity constants with the type being stored in `ObservedAggregates`.
 pub trait Consts {
@@ -69,10 +79,81 @@ impl<T: EthSpec> Consts for SyncCommitteeContribution<T> {
     }
 }
 
+/// A trait for types that implement a behaviour where one object of that type
+/// can be a subset/superset of another.
+/// This trait allows us to be generic over the aggregate item that we store in the cache that
+/// we want to prevent duplicates/subsets for.
+pub trait SubsetItem {
+    /// The item that is stored for later comparison with new incoming aggregate items.
+    type Item;
+
+    /// Returns `true` if `self` is a non-strict subset of `other` and `false` otherwise.
+    fn is_subset(&self, other: &Self::Item) -> bool;
+
+    /// Returns `true` if `self` is a non-strict superset of `other` and `false` otherwise.
+    fn is_superset(&self, other: &Self::Item) -> bool;
+
+    /// Returns the item that gets stored in `ObservedAggregates` for later subset
+    /// comparison with incoming aggregates.
+    fn get_item(&self) -> Self::Item;
+
+    /// Returns a unique value that keys the object to the item that is being stored
+    /// in `ObservedAggregates`.
+    fn root(&self) -> Hash256;
+}
+
+impl<T: EthSpec> SubsetItem for Attestation<T> {
+    type Item = BitList<T::MaxValidatorsPerCommittee>;
+    fn is_subset(&self, other: &Self::Item) -> bool {
+        self.aggregation_bits.is_subset(other)
+    }
+
+    fn is_superset(&self, other: &Self::Item) -> bool {
+        other.is_subset(&self.aggregation_bits)
+    }
+
+    /// Returns the sync contribution aggregation bits.
+    fn get_item(&self) -> Self::Item {
+        self.aggregation_bits.clone()
+    }
+
+    /// Returns the hash tree root of the attestation data.
+    fn root(&self) -> Hash256 {
+        self.data.tree_hash_root()
+    }
+}
+
+impl<T: EthSpec> SubsetItem for SyncCommitteeContribution<T> {
+    type Item = BitVector<T::SyncSubcommitteeSize>;
+    fn is_subset(&self, other: &Self::Item) -> bool {
+        self.aggregation_bits.is_subset(other)
+    }
+
+    fn is_superset(&self, other: &Self::Item) -> bool {
+        other.is_subset(&self.aggregation_bits)
+    }
+
+    /// Returns the sync contribution aggregation bits.
+    fn get_item(&self) -> Self::Item {
+        self.aggregation_bits.clone()
+    }
+
+    /// Returns the hash tree root of the root, slot and subcommittee index
+    /// of the sync contribution.
+    fn root(&self) -> Hash256 {
+        SyncCommitteeData {
+            root: self.beacon_block_root,
+            slot: self.slot,
+            subcommittee_index: self.subcommittee_index,
+        }
+        .tree_hash_root()
+    }
+}
+
 #[derive(Debug, PartialEq)]
 pub enum ObserveOutcome {
-    /// This item was already known.
-    AlreadyKnown,
+    /// This item is a non-strict subset of an already known item.
+    Subset,
     /// This was the first time this item was observed.
     New,
 }
@@ -94,26 +175,28 @@ pub enum Error {
     },
 }
 
-/// A `HashSet` that contains entries related to some `Slot`.
-struct SlotHashSet {
-    set: HashSet<Hash256>,
+/// A `HashMap` that contains entries related to some `Slot`.
+struct SlotHashSet<I> {
+    /// Contains a vector of maximally-sized aggregation bitfields/bitvectors
+    /// such that no bitfield/bitvector is a subset of any other in the list.
+    map: HashMap<Hash256, Vec<I>>,
     slot: Slot,
     max_capacity: usize,
 }
 
-impl SlotHashSet {
+impl<I> SlotHashSet<I> {
     pub fn new(slot: Slot, initial_capacity: usize, max_capacity: usize) -> Self {
         Self {
             slot,
-            set: HashSet::with_capacity(initial_capacity),
+            map: HashMap::with_capacity(initial_capacity),
             max_capacity,
         }
     }
 
     /// Store the items in self so future observations recognise its existence.
-    pub fn observe_item<T: SlotData>(
+    pub fn observe_item<S: SlotData + SubsetItem<Item = I>>(
         &mut self,
-        item: &T,
+        item: &S,
         root: Hash256,
     ) -> Result<ObserveOutcome, Error> {
         if item.get_slot() != self.slot {
@@ -123,29 +206,45 @@ impl SlotHashSet {
             });
         }
 
-        if self.set.contains(&root) {
-            Ok(ObserveOutcome::AlreadyKnown)
-        } else {
-            // Here we check to see if this slot has reached the maximum observation count.
-            //
-            // The resulting behaviour is that we are no longer able to successfully observe new
-            // items, however we will continue to return `is_known` values. We could also
-            // disable `is_known`, however then we would stop forwarding items across the
-            // gossip network and I think that this is a worse case than sending some invalid ones.
-            // The underlying libp2p network is responsible for removing duplicate messages, so
-            // this doesn't risk a broadcast loop.
-            if self.set.len() >= self.max_capacity {
-                return Err(Error::ReachedMaxObservationsPerSlot(self.max_capacity));
+        if let Some(aggregates) = self.map.get_mut(&root) {
+            for existing in aggregates {
+                // Check if `item` is a subset of any of the observed aggregates
+                if item.is_subset(existing) {
+                    return Ok(ObserveOutcome::Subset);
+                // Check if `item` is a superset of any of the observed aggregates
+                // If true, we replace the new item with its existing subset. This allows us
+                // to hold fewer items in the list.
+                } else if item.is_superset(existing) {
+                    *existing = item.get_item();
+                    return Ok(ObserveOutcome::New);
+                }
             }
-
-            self.set.insert(root);
-
-            Ok(ObserveOutcome::New)
         }
+
+        // Here we check to see if this slot has reached the maximum observation count.
+        //
+        // The resulting behaviour is that we are no longer able to successfully observe new
+        // items, however we will continue to return `is_known_subset` values. We could also
+        // disable `is_known_subset`, however then we would stop forwarding items across the
+        // gossip network and I think that this is a worse case than sending some invalid ones.
+        // The underlying libp2p network is responsible for removing duplicate messages, so
+        // this doesn't risk a broadcast loop.
+        if self.map.len() >= self.max_capacity {
+            return Err(Error::ReachedMaxObservationsPerSlot(self.max_capacity));
+        }
+
+        let item = item.get_item();
+        self.map.entry(root).or_default().push(item);
+        Ok(ObserveOutcome::New)
     }
 
-    /// Indicates if `item` has been observed before.
-    pub fn is_known<T: SlotData>(&self, item: &T, root: Hash256) -> Result<bool, Error> {
+    /// Check if `item` is a non-strict subset of any of the already observed aggregates for
+    /// the given root and slot.
+    pub fn is_known_subset<S: SlotData + SubsetItem<Item = I>>(
+        &self,
+        item: &S,
+        root: Hash256,
+    ) -> Result<bool, Error> {
         if item.get_slot() != self.slot {
             return Err(Error::IncorrectSlot {
                 expected: self.slot,
@@ -153,25 +252,28 @@ impl SlotHashSet {
             });
         }
 
-        Ok(self.set.contains(&root))
+        Ok(self
+            .map
+            .get(&root)
+            .map_or(false, |agg| agg.iter().any(|val| item.is_subset(val))))
     }
 
     /// The number of observed items in `self`.
     pub fn len(&self) -> usize {
-        self.set.len()
+        self.map.len()
     }
 }
 
 /// Stores the roots of objects for some number of `Slots`, so we can determine if
 /// these have previously been seen on the network.
-pub struct ObservedAggregates<T: TreeHash + SlotData + Consts, E: EthSpec> {
+pub struct ObservedAggregates<T: SlotData + Consts, E: EthSpec, I> {
     lowest_permissible_slot: Slot,
-    sets: Vec<SlotHashSet>,
+    sets: Vec<SlotHashSet<I>>,
     _phantom_spec: PhantomData<E>,
     _phantom_tree_hash: PhantomData<T>,
 }
 
-impl<T: TreeHash + SlotData + Consts, E: EthSpec> Default for ObservedAggregates<T, E> {
+impl<T: SlotData + Consts, E: EthSpec, I> Default for ObservedAggregates<T, E, I> {
     fn default() -> Self {
         Self {
             lowest_permissible_slot: Slot::new(0),
@@ -182,17 +284,17 @@ impl<T: TreeHash + SlotData + Consts, E: EthSpec> Default for ObservedAggregates
     }
 }
 
-impl<T: TreeHash + SlotData + Consts, E: EthSpec> ObservedAggregates<T, E> {
-    /// Store the root of `item` in `self`.
+impl<T: SlotData + Consts + SubsetItem<Item = I>, E: EthSpec, I> ObservedAggregates<T, E, I> {
+    /// Store `item` in `self` keyed at `root`.
     ///
-    /// `root` must equal `item.tree_hash_root()`.
+    /// `root` must equal `item.root::<SubsetItem>()`.
     pub fn observe_item(
         &mut self,
         item: &T,
         root_opt: Option<Hash256>,
     ) -> Result<ObserveOutcome, Error> {
         let index = self.get_set_index(item.get_slot())?;
-        let root = root_opt.unwrap_or_else(|| item.tree_hash_root());
+        let root = root_opt.unwrap_or_else(|| item.root());
 
         self.sets
             .get_mut(index)
@@ -200,17 +302,18 @@ impl<T: TreeHash + SlotData + Consts, E: EthSpec> ObservedAggregates<T, E> {
             .and_then(|set| set.observe_item(item, root))
     }
 
-    /// Check to see if the `root` of `item` is in self.
+    /// Check if `item` is a non-strict subset of any of the already observed aggregates for
+    /// the given root and slot.
     ///
-    /// `root` must equal `a.tree_hash_root()`.
+    /// `root` must equal `item.root::<SubsetItem>()`.
     #[allow(clippy::wrong_self_convention)]
-    pub fn is_known(&mut self, item: &T, root: Hash256) -> Result<bool, Error> {
+    pub fn is_known_subset(&mut self, item: &T, root: Hash256) -> Result<bool, Error> {
         let index = self.get_set_index(item.get_slot())?;
 
         self.sets
             .get(index)
             .ok_or(Error::InvalidSetIndex(index))
-            .and_then(|set| set.is_known(item, root))
+            .and_then(|set| set.is_known_subset(item, root))
     }
 
     /// The maximum number of slots that items are stored for.
@@ -296,7 +399,6 @@ impl<T: TreeHash + SlotData + Consts, E: EthSpec> ObservedAggregates<T, E> {
 #[cfg(not(debug_assertions))]
 mod tests {
     use super::*;
-    use tree_hash::TreeHash;
     use types::{test_utils::test_random_instance, Hash256};
 
     type E = types::MainnetEthSpec;
@@ -330,7 +432,7 @@ mod tests {
 
                     for a in &items {
                         assert_eq!(
-                            store.is_known(a, a.tree_hash_root()),
+                            store.is_known_subset(a, a.root()),
                             Ok(false),
                             "should indicate an unknown attestation is unknown"
                         );
@@ -343,13 +445,13 @@ mod tests {
 
                     for a in &items {
                         assert_eq!(
-                            store.is_known(a, a.tree_hash_root()),
+                            store.is_known_subset(a, a.root()),
                             Ok(true),
                             "should indicate a known attestation is known"
                         );
                         assert_eq!(
-                            store.observe_item(a, Some(a.tree_hash_root())),
-                            Ok(ObserveOutcome::AlreadyKnown),
+                            store.observe_item(a, Some(a.root())),
+                            Ok(ObserveOutcome::Subset),
                             "should acknowledge an existing attestation"
                         );
                     }
diff --git a/beacon_node/beacon_chain/src/sync_committee_verification.rs b/beacon_node/beacon_chain/src/sync_committee_verification.rs
index 14cdc2400..246bb12cc 100644
--- a/beacon_node/beacon_chain/src/sync_committee_verification.rs
+++ b/beacon_node/beacon_chain/src/sync_committee_verification.rs
@@ -37,6 +37,7 @@ use bls::{verify_signature_sets, PublicKeyBytes};
 use derivative::Derivative;
 use safe_arith::ArithError;
 use slot_clock::SlotClock;
+use ssz_derive::{Decode, Encode};
 use state_processing::per_block_processing::errors::SyncCommitteeMessageValidationError;
 use state_processing::signature_sets::{
     signed_sync_aggregate_selection_proof_signature_set, signed_sync_aggregate_signature_set,
@@ -47,6 +48,7 @@ use std::borrow::Cow;
 use std::collections::HashMap;
 use strum::AsRefStr;
 use tree_hash::TreeHash;
+use tree_hash_derive::TreeHash;
 use types::consts::altair::SYNC_COMMITTEE_SUBNET_COUNT;
 use types::slot_data::SlotData;
 use types::sync_committee::Error as SyncCommitteeError;
@@ -110,14 +112,14 @@ pub enum Error {
     ///
     /// The peer has sent an invalid message.
     AggregatorPubkeyUnknown(u64),
-    /// The sync contribution has been seen before; either in a block, on the gossip network or from a
-    /// local validator.
+    /// The sync contribution or a superset of this sync contribution's aggregation bits for the same data
+    /// has been seen before; either in a block on the gossip network or from a local validator.
     ///
     /// ## Peer scoring
     ///
     /// It's unclear if this sync contribution is valid, however we have already observed it and do not
     /// need to observe it again.
-    SyncContributionAlreadyKnown(Hash256),
+    SyncContributionSupersetKnown(Hash256),
     /// There has already been an aggregation observed for this validator, we refuse to process a
     /// second.
     ///
@@ -268,6 +270,14 @@ pub struct VerifiedSyncContribution<T: BeaconChainTypes> {
     participant_pubkeys: Vec<PublicKeyBytes>,
 }
 
+/// The sync contribution data.
+#[derive(Encode, Decode, TreeHash)]
+pub struct SyncCommitteeData {
+    pub slot: Slot,
+    pub root: Hash256,
+    pub subcommittee_index: u64,
+}
+
 /// Wraps a `SyncCommitteeMessage` that has been verified for propagation on the gossip network.
 #[derive(Clone)]
 pub struct VerifiedSyncCommitteeMessage {
@@ -314,15 +324,22 @@ impl<T: BeaconChainTypes> VerifiedSyncContribution<T> {
             return Err(Error::AggregatorNotInCommittee { aggregator_index });
         };
 
-        // Ensure the valid sync contribution has not already been seen locally.
-        let contribution_root = contribution.tree_hash_root();
+        // Ensure the valid sync contribution or its superset has not already been seen locally.
+        let contribution_data_root = SyncCommitteeData {
+            slot: contribution.slot,
+            root: contribution.beacon_block_root,
+            subcommittee_index: contribution.subcommittee_index,
+        }
+        .tree_hash_root();
+
         if chain
             .observed_sync_contributions
             .write()
-            .is_known(contribution, contribution_root)
+            .is_known_subset(contribution, contribution_data_root)
             .map_err(|e| Error::BeaconChainError(e.into()))?
         {
-            return Err(Error::SyncContributionAlreadyKnown(contribution_root));
+            metrics::inc_counter(&metrics::SYNC_CONTRIBUTION_SUBSETS);
+            return Err(Error::SyncContributionSupersetKnown(contribution_data_root));
         }
 
         // Ensure there has been no other observed aggregate for the given `aggregator_index`.
@@ -376,13 +393,14 @@ impl<T: BeaconChainTypes> VerifiedSyncContribution<T> {
         //
         // It's important to double check that the contribution is not already known, otherwise two
         // contribution processed at the same time could be published.
-        if let ObserveOutcome::AlreadyKnown = chain
+        if let ObserveOutcome::Subset = chain
             .observed_sync_contributions
             .write()
-            .observe_item(contribution, Some(contribution_root))
+            .observe_item(contribution, Some(contribution_data_root))
             .map_err(|e| Error::BeaconChainError(e.into()))?
         {
-            return Err(Error::SyncContributionAlreadyKnown(contribution_root));
+            metrics::inc_counter(&metrics::SYNC_CONTRIBUTION_SUBSETS);
+            return Err(Error::SyncContributionSupersetKnown(contribution_data_root));
         }
 
         // Observe the aggregator so we don't process another aggregate from them.
diff --git a/beacon_node/beacon_chain/tests/attestation_verification.rs b/beacon_node/beacon_chain/tests/attestation_verification.rs
index 1040521e5..5cea51090 100644
--- a/beacon_node/beacon_chain/tests/attestation_verification.rs
+++ b/beacon_node/beacon_chain/tests/attestation_verification.rs
@@ -699,8 +699,8 @@ async fn aggregated_gossip_verification() {
             |tester, err| {
                 assert!(matches!(
                     err,
-                    AttnError::AttestationAlreadyKnown(hash)
-                    if hash == tester.valid_aggregate.message.aggregate.tree_hash_root()
+                    AttnError::AttestationSupersetKnown(hash)
+                    if hash == tester.valid_aggregate.message.aggregate.data.tree_hash_root()
                 ))
             },
         )
diff --git a/beacon_node/beacon_chain/tests/sync_committee_verification.rs b/beacon_node/beacon_chain/tests/sync_committee_verification.rs
index 4204a5121..0e4745ff6 100644
--- a/beacon_node/beacon_chain/tests/sync_committee_verification.rs
+++ b/beacon_node/beacon_chain/tests/sync_committee_verification.rs
@@ -1,6 +1,6 @@
 #![cfg(not(debug_assertions))]
 
-use beacon_chain::sync_committee_verification::Error as SyncCommitteeError;
+use beacon_chain::sync_committee_verification::{Error as SyncCommitteeError, SyncCommitteeData};
 use beacon_chain::test_utils::{BeaconChainHarness, EphemeralHarnessType, RelativeSyncCommittee};
 use int_to_bytes::int_to_bytes32;
 use lazy_static::lazy_static;
@@ -444,11 +444,17 @@ async fn aggregated_gossip_verification() {
      * subcommittee index contribution.subcommittee_index.
      */
 
+    let contribution = &valid_aggregate.message.contribution;
+    let sync_committee_data = SyncCommitteeData {
+        slot: contribution.slot,
+        root: contribution.beacon_block_root,
+        subcommittee_index: contribution.subcommittee_index,
+    };
     assert_invalid!(
         "aggregate that has already been seen",
         valid_aggregate.clone(),
-        SyncCommitteeError::SyncContributionAlreadyKnown(hash)
-        if hash == valid_aggregate.message.contribution.tree_hash_root()
+        SyncCommitteeError::SyncContributionSupersetKnown(hash)
+        if hash == sync_committee_data.tree_hash_root()
     );
 
     /*
diff --git a/beacon_node/builder_client/src/lib.rs b/beacon_node/builder_client/src/lib.rs
index 255c2fdd1..c78f686d0 100644
--- a/beacon_node/builder_client/src/lib.rs
+++ b/beacon_node/builder_client/src/lib.rs
@@ -72,7 +72,7 @@ impl BuilderHttpClient {
             .await?
             .json()
             .await
-            .map_err(Error::Reqwest)
+            .map_err(Into::into)
     }
 
     /// Perform a HTTP GET request, returning the `Response` for further processing.
@@ -85,7 +85,7 @@ impl BuilderHttpClient {
         if let Some(timeout) = timeout {
             builder = builder.timeout(timeout);
         }
-        let response = builder.send().await.map_err(Error::Reqwest)?;
+        let response = builder.send().await.map_err(Error::from)?;
         ok_or_error(response).await
     }
 
@@ -114,7 +114,7 @@ impl BuilderHttpClient {
         if let Some(timeout) = timeout {
             builder = builder.timeout(timeout);
         }
-        let response = builder.json(body).send().await.map_err(Error::Reqwest)?;
+        let response = builder.json(body).send().await.map_err(Error::from)?;
         ok_or_error(response).await
     }
 
diff --git a/beacon_node/execution_layer/Cargo.toml b/beacon_node/execution_layer/Cargo.toml
index f561c972f..c27ed4c65 100644
--- a/beacon_node/execution_layer/Cargo.toml
+++ b/beacon_node/execution_layer/Cargo.toml
@@ -23,7 +23,7 @@ bytes = "1.1.0"
 task_executor = { path = "../../common/task_executor" }
 hex = "0.4.2"
 ethereum_ssz = "0.5.0"
-ssz_types = "0.5.0"
+ssz_types = "0.5.3"
 eth2 = { path = "../../common/eth2" }
 kzg = { path = "../../crypto/kzg" }
 state_processing = { path = "../../consensus/state_processing" }
@@ -51,3 +51,4 @@ keccak-hash = "0.10.0"
 hash256-std-hasher = "0.15.2"
 triehash = "0.8.4"
 hash-db = "0.15.2"
+pretty_reqwest_error = { path = "../../common/pretty_reqwest_error" }
\ No newline at end of file
diff --git a/beacon_node/execution_layer/src/engine_api.rs b/beacon_node/execution_layer/src/engine_api.rs
index 0a5d155f5..7528d232f 100644
--- a/beacon_node/execution_layer/src/engine_api.rs
+++ b/beacon_node/execution_layer/src/engine_api.rs
@@ -11,6 +11,7 @@ pub use ethers_core::types::Transaction;
 use ethers_core::utils::rlp::{self, Decodable, Rlp};
 use http::deposit_methods::RpcError;
 pub use json_structures::{JsonWithdrawal, TransitionConfigurationV1};
+use pretty_reqwest_error::PrettyReqwestError;
 use reqwest::StatusCode;
 use serde::{Deserialize, Serialize};
 use std::convert::TryFrom;
@@ -35,7 +36,7 @@ pub type PayloadId = [u8; 8];
 
 #[derive(Debug)]
 pub enum Error {
-    Reqwest(reqwest::Error),
+    HttpClient(PrettyReqwestError),
     Auth(auth::Error),
     BadResponse(String),
     RequestFailed(String),
@@ -70,7 +71,7 @@ impl From<reqwest::Error> for Error {
         ) {
             Error::Auth(auth::Error::InvalidToken)
         } else {
-            Error::Reqwest(e)
+            Error::HttpClient(e.into())
         }
     }
 }
diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
index 3edc6aa30..a4fea8f5f 100644
--- a/beacon_node/http_api/src/lib.rs
+++ b/beacon_node/http_api/src/lib.rs
@@ -2882,7 +2882,7 @@ pub fn serve<T: BeaconChainTypes>(
                             // It's reasonably likely that two different validators produce
                             // identical aggregates, especially if they're using the same beacon
                             // node.
-                            Err(AttnError::AttestationAlreadyKnown(_)) => continue,
+                            Err(AttnError::AttestationSupersetKnown(_)) => continue,
                             // If we've already seen this aggregator produce an aggregate, just
                             // skip this one.
                             //
diff --git a/beacon_node/http_api/src/sync_committees.rs b/beacon_node/http_api/src/sync_committees.rs
index c728fbeb1..07dfb5c98 100644
--- a/beacon_node/http_api/src/sync_committees.rs
+++ b/beacon_node/http_api/src/sync_committees.rs
@@ -304,7 +304,7 @@ pub fn process_signed_contribution_and_proofs<T: BeaconChainTypes>(
             }
             // If we already know the contribution, don't broadcast it or attempt to
             // further verify it. Return success.
-            Err(SyncVerificationError::SyncContributionAlreadyKnown(_)) => continue,
+            Err(SyncVerificationError::SyncContributionSupersetKnown(_)) => continue,
             // If we've already seen this aggregator produce an aggregate, just
             // skip this one.
             //
diff --git a/beacon_node/lighthouse_network/Cargo.toml b/beacon_node/lighthouse_network/Cargo.toml
index ca15b5ef2..6d056d835 100644
--- a/beacon_node/lighthouse_network/Cargo.toml
+++ b/beacon_node/lighthouse_network/Cargo.toml
@@ -8,7 +8,7 @@ edition = "2021"
 discv5 = { version = "0.3.0", features = ["libp2p"]}
 unsigned-varint = { version = "0.6.0", features = ["codec"] }
 types = { path =  "../../consensus/types" }
-ssz_types = "0.5.0"
+ssz_types = "0.5.3"
 serde = { version = "1.0.116", features = ["derive"] }
 serde_derive = "1.0.116"
 ethereum_ssz = "0.5.0"
diff --git a/beacon_node/network/Cargo.toml b/beacon_node/network/Cargo.toml
index 3673a8a09..cb6d1116c 100644
--- a/beacon_node/network/Cargo.toml
+++ b/beacon_node/network/Cargo.toml
@@ -22,7 +22,7 @@ slot_clock = { path = "../../common/slot_clock" }
 slog = { version = "2.5.2", features = ["max_level_trace", "nested-values"] }
 hex = "0.4.2"
 ethereum_ssz = "0.5.0"
-ssz_types = "0.5.0"
+ssz_types = "0.5.3"
 futures = "0.3.7"
 error-chain = "0.12.4"
 tokio = { version = "1.14.0", features = ["full"] }
diff --git a/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs b/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs
index a42378c1d..582f403cc 100644
--- a/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs
+++ b/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs
@@ -1893,7 +1893,7 @@ impl<T: BeaconChainTypes> Worker<T> {
                     "attn_agg_not_in_committee",
                 );
             }
-            AttnError::AttestationAlreadyKnown { .. } => {
+            AttnError::AttestationSupersetKnown { .. } => {
                 /*
                  * The aggregate attestation has already been observed on the network or in
                  * a block.
@@ -2405,7 +2405,7 @@ impl<T: BeaconChainTypes> Worker<T> {
                     "sync_bad_aggregator",
                 );
             }
-            SyncCommitteeError::SyncContributionAlreadyKnown(_)
+            SyncCommitteeError::SyncContributionSupersetKnown(_)
             | SyncCommitteeError::AggregatorAlreadyKnown(_) => {
                 /*
                  * The sync committee message already been observed on the network or in
diff --git a/common/eth2/Cargo.toml b/common/eth2/Cargo.toml
index 4eabd3ff8..d8e1a375f 100644
--- a/common/eth2/Cargo.toml
+++ b/common/eth2/Cargo.toml
@@ -27,6 +27,11 @@ futures = "0.3.8"
 store = { path = "../../beacon_node/store", optional = true }
 slashing_protection = { path = "../../validator_client/slashing_protection", optional = true }
 mediatype = "0.19.13"
+mime = "0.3.16"
+pretty_reqwest_error = { path = "../../common/pretty_reqwest_error" }
+
+[dev-dependencies]
+tokio = { version = "1.14.0", features = ["full"] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
 psutil = { version = "3.2.2", optional = true }
diff --git a/common/eth2/src/lib.rs b/common/eth2/src/lib.rs
index 3b0c527f6..98eb1eba9 100644
--- a/common/eth2/src/lib.rs
+++ b/common/eth2/src/lib.rs
@@ -19,6 +19,7 @@ use self::types::{Error as ResponseError, *};
 use futures::Stream;
 use futures_util::StreamExt;
 use lighthouse_network::PeerId;
+use pretty_reqwest_error::PrettyReqwestError;
 pub use reqwest;
 use reqwest::{IntoUrl, RequestBuilder, Response};
 pub use reqwest::{StatusCode, Url};
@@ -39,7 +40,7 @@ pub const CONSENSUS_VERSION_HEADER: &str = "Eth-Consensus-Version";
 #[derive(Debug)]
 pub enum Error {
     /// The `reqwest` client raised an error.
-    Reqwest(reqwest::Error),
+    HttpClient(PrettyReqwestError),
     /// The server returned an error message where the body was able to be parsed.
     ServerMessage(ErrorMessage),
     /// The server returned an error message with an array of errors.
@@ -70,7 +71,7 @@ pub enum Error {
 
 impl From<reqwest::Error> for Error {
     fn from(error: reqwest::Error) -> Self {
-        Error::Reqwest(error)
+        Error::HttpClient(error.into())
     }
 }
 
@@ -78,7 +79,7 @@ impl Error {
     /// If the error has a HTTP status code, return it.
     pub fn status(&self) -> Option<StatusCode> {
         match self {
-            Error::Reqwest(error) => error.status(),
+            Error::HttpClient(error) => error.inner().status(),
             Error::ServerMessage(msg) => StatusCode::try_from(msg.code).ok(),
             Error::ServerIndexedMessage(msg) => StatusCode::try_from(msg.code).ok(),
             Error::StatusCode(status) => Some(*status),
@@ -278,7 +279,7 @@ impl BeaconNodeHttpClient {
             .await?
             .json()
             .await
-            .map_err(Error::Reqwest)
+            .map_err(Into::into)
     }
 
     /// Perform a HTTP POST request with a custom timeout.
@@ -303,7 +304,7 @@ impl BeaconNodeHttpClient {
             .await?
             .json()
             .await
-            .map_err(Error::Reqwest)
+            .map_err(Error::from)
     }
 
     /// Generic POST function supporting arbitrary responses and timeouts.
@@ -1673,7 +1674,7 @@ impl BeaconNodeHttpClient {
             .bytes_stream()
             .map(|next| match next {
                 Ok(bytes) => EventKind::from_sse_bytes(bytes.as_ref()),
-                Err(e) => Err(Error::Reqwest(e)),
+                Err(e) => Err(Error::HttpClient(e.into())),
             }))
     }
 
diff --git a/common/eth2/src/lighthouse.rs b/common/eth2/src/lighthouse.rs
index bb933dbe1..1b4bcc0e3 100644
--- a/common/eth2/src/lighthouse.rs
+++ b/common/eth2/src/lighthouse.rs
@@ -364,12 +364,12 @@ pub struct DatabaseInfo {
 impl BeaconNodeHttpClient {
     /// Perform a HTTP GET request, returning `None` on a 404 error.
     async fn get_bytes_opt<U: IntoUrl>(&self, url: U) -> Result<Option<Vec<u8>>, Error> {
-        let response = self.client.get(url).send().await.map_err(Error::Reqwest)?;
+        let response = self.client.get(url).send().await.map_err(Error::from)?;
         match ok_or_error(response).await {
             Ok(resp) => Ok(Some(
                 resp.bytes()
                     .await
-                    .map_err(Error::Reqwest)?
+                    .map_err(Error::from)?
                     .into_iter()
                     .collect::<Vec<_>>(),
             )),
diff --git a/common/eth2/src/lighthouse_vc/http_client.rs b/common/eth2/src/lighthouse_vc/http_client.rs
index 720d8c779..cd7873c9b 100644
--- a/common/eth2/src/lighthouse_vc/http_client.rs
+++ b/common/eth2/src/lighthouse_vc/http_client.rs
@@ -170,7 +170,7 @@ impl ValidatorClientHttpClient {
             .map_err(|_| Error::InvalidSignatureHeader)?
             .to_string();
 
-        let body = response.bytes().await.map_err(Error::Reqwest)?;
+        let body = response.bytes().await.map_err(Error::from)?;
 
         let message =
             Message::parse_slice(digest(&SHA256, &body).as_ref()).expect("sha256 is 32 bytes");
@@ -222,7 +222,7 @@ impl ValidatorClientHttpClient {
             .headers(self.headers()?)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         ok_or_error(response).await
     }
 
@@ -236,7 +236,7 @@ impl ValidatorClientHttpClient {
             .await?
             .json()
             .await
-            .map_err(Error::Reqwest)
+            .map_err(Error::from)
     }
 
     /// Perform a HTTP GET request, returning `None` on a 404 error.
@@ -266,7 +266,7 @@ impl ValidatorClientHttpClient {
             .json(body)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         ok_or_error(response).await
     }
 
@@ -297,7 +297,7 @@ impl ValidatorClientHttpClient {
             .json(body)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         let response = ok_or_error(response).await?;
         self.signed_body(response).await?;
         Ok(())
@@ -316,7 +316,7 @@ impl ValidatorClientHttpClient {
             .json(body)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         ok_or_error(response).await
     }
 
diff --git a/common/eth2_network_config/built_in_network_configs/gnosis/config.yaml b/common/eth2_network_config/built_in_network_configs/gnosis/config.yaml
index 07e615930..0ac70bcd6 100644
--- a/common/eth2_network_config/built_in_network_configs/gnosis/config.yaml
+++ b/common/eth2_network_config/built_in_network_configs/gnosis/config.yaml
@@ -38,7 +38,7 @@ BELLATRIX_FORK_VERSION: 0x02000064
 BELLATRIX_FORK_EPOCH: 385536
 # Capella
 CAPELLA_FORK_VERSION: 0x03000064
-CAPELLA_FORK_EPOCH: 18446744073709551615
+CAPELLA_FORK_EPOCH: 648704
 # Deneb
 DENEB_FORK_VERSION: 0x04000064
 DENEB_FORK_EPOCH: 18446744073709551615
diff --git a/common/pretty_reqwest_error/Cargo.toml b/common/pretty_reqwest_error/Cargo.toml
new file mode 100644
index 000000000..ca9f4812b
--- /dev/null
+++ b/common/pretty_reqwest_error/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "pretty_reqwest_error"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+reqwest = { version = "0.11.0", features = ["json","stream"] }
+sensitive_url = { path = "../sensitive_url" }
diff --git a/common/pretty_reqwest_error/src/lib.rs b/common/pretty_reqwest_error/src/lib.rs
new file mode 100644
index 000000000..4c605f38a
--- /dev/null
+++ b/common/pretty_reqwest_error/src/lib.rs
@@ -0,0 +1,62 @@
+use sensitive_url::SensitiveUrl;
+use std::error::Error as StdError;
+use std::fmt;
+
+pub struct PrettyReqwestError(reqwest::Error);
+
+impl PrettyReqwestError {
+    pub fn inner(&self) -> &reqwest::Error {
+        &self.0
+    }
+}
+
+impl fmt::Debug for PrettyReqwestError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if let Some(url) = self.0.url() {
+            if let Ok(url) = SensitiveUrl::new(url.clone()) {
+                write!(f, "url: {}", url)?;
+            } else {
+                write!(f, "url: unable_to_parse")?;
+            };
+        }
+
+        let kind = if self.0.is_builder() {
+            "builder"
+        } else if self.0.is_redirect() {
+            "redirect"
+        } else if self.0.is_status() {
+            "status"
+        } else if self.0.is_timeout() {
+            "timeout"
+        } else if self.0.is_request() {
+            "request"
+        } else if self.0.is_connect() {
+            "connect"
+        } else if self.0.is_body() {
+            "body"
+        } else if self.0.is_decode() {
+            "decode"
+        } else {
+            "unknown"
+        };
+        write!(f, ", kind: {}", kind)?;
+
+        if let Some(status) = self.0.status() {
+            write!(f, ", status_code: {}", status)?;
+        }
+
+        if let Some(ref source) = self.0.source() {
+            write!(f, ", detail: {}", source)?;
+        } else {
+            write!(f, ", source: unknown")?;
+        }
+
+        Ok(())
+    }
+}
+
+impl From<reqwest::Error> for PrettyReqwestError {
+    fn from(inner: reqwest::Error) -> Self {
+        Self(inner)
+    }
+}
diff --git a/common/sensitive_url/src/lib.rs b/common/sensitive_url/src/lib.rs
index b6705eb60..b6068a2dc 100644
--- a/common/sensitive_url/src/lib.rs
+++ b/common/sensitive_url/src/lib.rs
@@ -75,7 +75,7 @@ impl SensitiveUrl {
         SensitiveUrl::new(surl)
     }
 
-    fn new(full: Url) -> Result<Self, SensitiveError> {
+    pub fn new(full: Url) -> Result<Self, SensitiveError> {
         let mut redacted = full.clone();
         redacted
             .path_segments_mut()
diff --git a/consensus/cached_tree_hash/Cargo.toml b/consensus/cached_tree_hash/Cargo.toml
index c2856003b..0f43c8890 100644
--- a/consensus/cached_tree_hash/Cargo.toml
+++ b/consensus/cached_tree_hash/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2021"
 
 [dependencies]
 ethereum-types = "0.14.1"
-ssz_types = "0.5.0"
+ssz_types = "0.5.3"
 ethereum_hashing = "1.0.0-beta.2"
 ethereum_ssz_derive = "0.5.0"
 ethereum_ssz = "0.5.0"
diff --git a/consensus/state_processing/Cargo.toml b/consensus/state_processing/Cargo.toml
index c16742782..f19cd1d29 100644
--- a/consensus/state_processing/Cargo.toml
+++ b/consensus/state_processing/Cargo.toml
@@ -15,7 +15,7 @@ integer-sqrt = "0.1.5"
 itertools = "0.10.0"
 ethereum_ssz = "0.5.0"
 ethereum_ssz_derive = "0.5.0"
-ssz_types = "0.5.0"
+ssz_types = "0.5.3"
 merkle_proof = { path = "../merkle_proof" }
 safe_arith = { path = "../safe_arith" }
 tree_hash = "0.5.0"
diff --git a/consensus/types/Cargo.toml b/consensus/types/Cargo.toml
index 65883bd27..8fdb21a06 100644
--- a/consensus/types/Cargo.toml
+++ b/consensus/types/Cargo.toml
@@ -28,7 +28,7 @@ serde_derive = "1.0.116"
 slog = "2.5.2"
 ethereum_ssz = { version = "0.5.0", features = ["arbitrary"] }
 ethereum_ssz_derive = "0.5.0"
-ssz_types = { version = "0.5.0", features = ["arbitrary"] }
+ssz_types = { version = "0.5.3", features = ["arbitrary"] }
 swap_or_not_shuffle = { path = "../swap_or_not_shuffle", features = ["arbitrary"] }
 test_random_derive = { path = "../../common/test_random_derive" }
 tree_hash = { version = "0.5.0", features = ["arbitrary"] }
diff --git a/consensus/types/src/chain_spec.rs b/consensus/types/src/chain_spec.rs
index e510b0a27..2d5b51e5f 100644
--- a/consensus/types/src/chain_spec.rs
+++ b/consensus/types/src/chain_spec.rs
@@ -856,7 +856,7 @@ impl ChainSpec {
              * Capella hard fork params
              */
             capella_fork_version: [0x03, 0x00, 0x00, 0x64],
-            capella_fork_epoch: None,
+            capella_fork_epoch: Some(Epoch::new(648704)),
             max_validators_per_withdrawals_sweep: 8192,
 
             /*