diff --git a/cmd/geth/consolecmd_test.go b/cmd/geth/consolecmd_test.go
index f4e8bf490..d5ebd74ae 100644
--- a/cmd/geth/consolecmd_test.go
+++ b/cmd/geth/consolecmd_test.go
@@ -41,7 +41,7 @@ func runMinimalGeth(t *testing.T, args ...string) *testgeth {
 	// --ropsten to make the 'writing genesis to disk' faster (no accounts)
 	// --networkid=1337 to avoid cache bump
 	// --syncmode=full to avoid allocating fast sync bloom
-	allArgs := []string{"--ropsten", "--networkid", "1337", "--syncmode=full", "--port", "0",
+	allArgs := []string{"--ropsten", "--networkid", "1337", "--authrpc.port", "0", "--syncmode=full", "--port", "0",
 		"--nat", "none", "--nodiscover", "--maxpeers", "0", "--cache", "64",
 		"--datadir.minfreedisk", "0"}
 	return runGeth(t, append(allArgs, args...)...)
diff --git a/cmd/geth/genesis_test.go b/cmd/geth/genesis_test.go
index c95755f2d..7667a8581 100644
--- a/cmd/geth/genesis_test.go
+++ b/cmd/geth/genesis_test.go
@@ -83,7 +83,7 @@ func TestCustomGenesis(t *testing.T) {
 
 		// Query the custom genesis block
 		geth := runGeth(t, "--networkid", "1337", "--syncmode=full", "--cache", "16",
-			"--datadir", datadir, "--maxpeers", "0", "--port", "0",
+			"--datadir", datadir, "--maxpeers", "0", "--port", "0", "--authrpc.port", "0",
 			"--nodiscover", "--nat", "none", "--ipcdisable",
 			"--exec", tt.query, "console")
 		geth.ExpectRegexp(tt.result)
diff --git a/cmd/geth/les_test.go b/cmd/geth/les_test.go
index d86f41054..d06c3b91d 100644
--- a/cmd/geth/les_test.go
+++ b/cmd/geth/les_test.go
@@ -111,7 +111,7 @@ var nextIPC = uint32(0)
 
 func startGethWithIpc(t *testing.T, name string, args ...string) *gethrpc {
 	ipcName := fmt.Sprintf("geth-%d.ipc", atomic.AddUint32(&nextIPC, 1))
-	args = append([]string{"--networkid=42", "--port=0", "--ipcpath", ipcName}, args...)
+	args = append([]string{"--networkid=42", "--port=0", "--authrpc.port", "0", "--ipcpath", ipcName}, args...)
 	t.Logf("Starting %v with rpc: %v", name, args)
 
 	g := &gethrpc{
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 47637a9dd..68ef05fa2 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -1993,10 +1993,8 @@ func RegisterEthService(stack *node.Node, cfg *ethconfig.Config) (ethapi.Backend
 			Fatalf("Failed to register the Ethereum service: %v", err)
 		}
 		stack.RegisterAPIs(tracers.APIs(backend.ApiBackend))
-		if backend.BlockChain().Config().TerminalTotalDifficulty != nil {
-			if err := lescatalyst.Register(stack, backend); err != nil {
-				Fatalf("Failed to register the catalyst service: %v", err)
-			}
+		if err := lescatalyst.Register(stack, backend); err != nil {
+			Fatalf("Failed to register the Engine API service: %v", err)
 		}
 		return backend.ApiBackend, nil
 	}
@@ -2010,10 +2008,8 @@ func RegisterEthService(stack *node.Node, cfg *ethconfig.Config) (ethapi.Backend
 			Fatalf("Failed to create the LES server: %v", err)
 		}
 	}
-	if backend.BlockChain().Config().TerminalTotalDifficulty != nil {
-		if err := ethcatalyst.Register(stack, backend); err != nil {
-			Fatalf("Failed to register the catalyst service: %v", err)
-		}
+	if err := ethcatalyst.Register(stack, backend); err != nil {
+		Fatalf("Failed to register the Engine API service: %v", err)
 	}
 	stack.RegisterAPIs(tracers.APIs(backend.APIBackend))
 	return backend.APIBackend, backend
diff --git a/eth/catalyst/api.go b/eth/catalyst/api.go
index feccff881..a72e1c41e 100644
--- a/eth/catalyst/api.go
+++ b/eth/catalyst/api.go
@@ -37,9 +37,9 @@ import (
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
-// Register adds catalyst APIs to the full node.
+// Register adds the engine API to the full node.
 func Register(stack *node.Node, backend *eth.Ethereum) error {
-	log.Warn("Catalyst mode enabled", "protocol", "eth")
+	log.Warn("Engine API enabled", "protocol", "eth")
 	stack.RegisterAPIs([]rpc.API{
 		{
 			Namespace:     "engine",
@@ -62,7 +62,7 @@ type ConsensusAPI struct {
 // The underlying blockchain needs to have a valid terminal total difficulty set.
 func NewConsensusAPI(eth *eth.Ethereum) *ConsensusAPI {
 	if eth.BlockChain().Config().TerminalTotalDifficulty == nil {
-		panic("Catalyst started without valid total difficulty")
+		log.Warn("Engine API started without valid total difficulty")
 	}
 	return &ConsensusAPI{
 		eth:          eth,
@@ -73,7 +73,7 @@ func NewConsensusAPI(eth *eth.Ethereum) *ConsensusAPI {
 
 // ForkchoiceUpdatedV1 has several responsibilities:
 // If the method is called with an empty head block:
-// 		we return success, which can be used to check if the catalyst mode is enabled
+// 		we return success, which can be used to check if the engine API is enabled
 // If the total difficulty was not reached:
 // 		we return INVALID
 // If the finalizedBlockHash is set:
@@ -223,7 +223,7 @@ func (api *ConsensusAPI) ExchangeTransitionConfigurationV1(config beacon.Transit
 		return nil, errors.New("invalid terminal total difficulty")
 	}
 	ttd := api.eth.BlockChain().Config().TerminalTotalDifficulty
-	if ttd.Cmp(config.TerminalTotalDifficulty.ToInt()) != 0 {
+	if ttd == nil || ttd.Cmp(config.TerminalTotalDifficulty.ToInt()) != 0 {
 		log.Warn("Invalid TTD configured", "geth", ttd, "beacon", config.TerminalTotalDifficulty)
 		return nil, fmt.Errorf("invalid ttd: execution %v consensus %v", ttd, config.TerminalTotalDifficulty)
 	}
diff --git a/les/catalyst/api.go b/les/catalyst/api.go
index 9c2d17c79..983fc7bff 100644
--- a/les/catalyst/api.go
+++ b/les/catalyst/api.go
@@ -50,7 +50,7 @@ type ConsensusAPI struct {
 // The underlying blockchain needs to have a valid terminal total difficulty set.
 func NewConsensusAPI(les *les.LightEthereum) *ConsensusAPI {
 	if les.BlockChain().Config().TerminalTotalDifficulty == nil {
-		panic("Catalyst started without valid total difficulty")
+		log.Warn("Catalyst started without valid total difficulty")
 	}
 	return &ConsensusAPI{les: les}
 }