diff --git a/chain/stmgr/forks.go b/chain/stmgr/forks.go
index 772a1a9a3..96873b675 100644
--- a/chain/stmgr/forks.go
+++ b/chain/stmgr/forks.go
@@ -21,6 +21,7 @@ import (
 
 	"github.com/filecoin-project/specs-actors/actors/migration/nv3"
 	m2 "github.com/filecoin-project/specs-actors/v2/actors/migration"
+	states2 "github.com/filecoin-project/specs-actors/v2/actors/states"
 
 	"github.com/filecoin-project/lotus/build"
 	"github.com/filecoin-project/lotus/chain/actors"
@@ -431,6 +432,19 @@ func UpgradeActorsV2(ctx context.Context, sm *StateManager, cb ExecCallback, roo
 		return cid.Undef, xerrors.Errorf("upgrading to actors v2: %w", err)
 	}
 
+	newStateTree, err := states2.LoadTree(store, newHamtRoot)
+	if err != nil {
+		return cid.Undef, xerrors.Errorf("failed to load new state tree: %w", err)
+	}
+
+	// Check all state-tree invariants.
+	if msgs, err := states2.CheckStateInvariants(newStateTree, types.TotalFilecoinInt); err != nil {
+		return cid.Undef, xerrors.Errorf("failed to check new state tree: %w", err)
+	} else if !msgs.IsEmpty() {
+		// This error is going to be really nasty.
+		return cid.Undef, xerrors.Errorf("network upgrade failed: %v", msgs.Messages())
+	}
+
 	newRoot, err := store.Put(ctx, &types.StateRoot{
 		// TODO: ActorUpgrade: should be state-tree specific, not just the actors version.
 		Version: actors.Version2,
@@ -441,7 +455,7 @@ func UpgradeActorsV2(ctx context.Context, sm *StateManager, cb ExecCallback, roo
 		return cid.Undef, xerrors.Errorf("failed to persist new state root: %w", err)
 	}
 
-	// perform some basic sanity checks.
+	// perform some basic sanity checks to make sure everything still works.
 	if newSm, err := state.LoadStateTree(store, newRoot); err != nil {
 		return cid.Undef, xerrors.Errorf("state tree sanity load failed: %w", err)
 	} else if newRoot2, err := newSm.Flush(ctx); err != nil {
diff --git a/go.mod b/go.mod
index 4908523fc..55f2fa308 100644
--- a/go.mod
+++ b/go.mod
@@ -37,7 +37,7 @@ require (
 	github.com/filecoin-project/go-statestore v0.1.0
 	github.com/filecoin-project/go-storedcounter v0.0.0-20200421200003-1c99c62e8a5b
 	github.com/filecoin-project/specs-actors v0.9.12-0.20200928180918-488a087c5add
-	github.com/filecoin-project/specs-actors/v2 v2.0.0-20200928175842-971c8d772684
+	github.com/filecoin-project/specs-actors/v2 v2.0.0-20200929004132-ea2d270c9f47
 	github.com/filecoin-project/specs-storage v0.1.1-0.20200907031224-ed2e5cd13796
 	github.com/filecoin-project/test-vectors/schema v0.0.1
 	github.com/gbrlsnchs/jwt/v3 v3.0.0-beta.1
diff --git a/go.sum b/go.sum
index 042b0d855..3413d730a 100644
--- a/go.sum
+++ b/go.sum
@@ -263,8 +263,8 @@ github.com/filecoin-project/specs-actors v0.9.7/go.mod h1:wM2z+kwqYgXn5Z7scV1YHL
 github.com/filecoin-project/specs-actors v0.9.9/go.mod h1:czlvLQGEX0fjLLfdNHD7xLymy6L3n7aQzRWzsYGf+ys=
 github.com/filecoin-project/specs-actors v0.9.12-0.20200928180918-488a087c5add h1:iXQOxr8uSyZ/qnTlOZf7ALp0io+jwLxmuWsNAk/YdoQ=
 github.com/filecoin-project/specs-actors v0.9.12-0.20200928180918-488a087c5add/go.mod h1:TS1AW/7LbG+615j4NsjMK1qlpAwaFsG9w0V2tg2gSao=
-github.com/filecoin-project/specs-actors/v2 v2.0.0-20200928175842-971c8d772684 h1:sjWZqblOOf1RaohI9w2R2AVp5uifNdzsusy7oVi5ioU=
-github.com/filecoin-project/specs-actors/v2 v2.0.0-20200928175842-971c8d772684/go.mod h1:/2Zra1BhLtpRywUhm++QP+3I5Ir+hBk/W24TpYjj43E=
+github.com/filecoin-project/specs-actors/v2 v2.0.0-20200929004132-ea2d270c9f47 h1:bt/CdGbF1Rq5rDVaMV+XWfHBRCxN7IxZfw6lC1v6KQM=
+github.com/filecoin-project/specs-actors/v2 v2.0.0-20200929004132-ea2d270c9f47/go.mod h1:/2Zra1BhLtpRywUhm++QP+3I5Ir+hBk/W24TpYjj43E=
 github.com/filecoin-project/specs-storage v0.1.1-0.20200907031224-ed2e5cd13796 h1:dJsTPWpG2pcTeojO2pyn0c6l+x/3MZYCBgo/9d11JEk=
 github.com/filecoin-project/specs-storage v0.1.1-0.20200907031224-ed2e5cd13796/go.mod h1:nJRRM7Aa9XVvygr3W9k6xGF46RWzr2zxF/iGoAIfA/g=
 github.com/filecoin-project/test-vectors/schema v0.0.1 h1:5fNF76nl4qolEvcIsjc0kUADlTMVHO73tW4kXXPnsus=