diff --git a/beacon-chain/rpc/eth/validator/validator.go b/beacon-chain/rpc/eth/validator/validator.go
index 25069c26e089..af5f5a042ffb 100644
--- a/beacon-chain/rpc/eth/validator/validator.go
+++ b/beacon-chain/rpc/eth/validator/validator.go
@@ -482,6 +482,9 @@ func (vs *Server) ProduceBlindedBlock(ctx context.Context, req *ethpbv1.ProduceB
 	ctx, span := trace.StartSpan(ctx, "validator.ProduceBlindedBlock")
 	defer span.End()
 
+	if !vs.V1Alpha1Server.BlockBuilder.Configured() {
+		return nil, status.Error(codes.Internal, "Block builder not configured")
+	}
 	if err := rpchelpers.ValidateSync(ctx, vs.SyncChecker, vs.HeadFetcher, vs.TimeFetcher, vs.OptimisticModeFetcher); err != nil {
 		// We simply return the error because it's already a gRPC error.
 		return nil, err
@@ -533,6 +536,10 @@ func (vs *Server) ProduceBlindedBlock(ctx context.Context, req *ethpbv1.ProduceB
 	if optimistic {
 		return nil, status.Errorf(codes.Unavailable, "The node is currently optimistic and cannot serve validators")
 	}
+	_, ok := v1alpha1resp.Block.(*ethpbalpha.GenericBeaconBlock_Bellatrix)
+	if ok {
+		return nil, status.Error(codes.Internal, "Prepared beacon block is not blinded")
+	}
 	bellatrixBlock, ok := v1alpha1resp.Block.(*ethpbalpha.GenericBeaconBlock_BlindedBellatrix)
 	if ok {
 		blk, err := migration.V1Alpha1BeaconBlockBlindedBellatrixToV2Blinded(bellatrixBlock.BlindedBellatrix)
@@ -546,6 +553,10 @@ func (vs *Server) ProduceBlindedBlock(ctx context.Context, req *ethpbv1.ProduceB
 			},
 		}, nil
 	}
+	_, ok = v1alpha1resp.Block.(*ethpbalpha.GenericBeaconBlock_Capella)
+	if ok {
+		return nil, status.Error(codes.Internal, "Prepared beacon block is not blinded")
+	}
 	capellaBlock, ok := v1alpha1resp.Block.(*ethpbalpha.GenericBeaconBlock_BlindedCapella)
 	if ok {
 		blk, err := migration.V1Alpha1BeaconBlockBlindedCapellaToV2Blinded(capellaBlock.BlindedCapella)
diff --git a/beacon-chain/rpc/eth/validator/validator_test.go b/beacon-chain/rpc/eth/validator/validator_test.go
index eeb4c7d34cff..fa53d3c7eb02 100644
--- a/beacon-chain/rpc/eth/validator/validator_test.go
+++ b/beacon-chain/rpc/eth/validator/validator_test.go
@@ -2271,6 +2271,7 @@ func TestProduceBlindedBlock(t *testing.T) {
 			SlashingsPool:     slashings.NewPool(),
 			ExitPool:          voluntaryexits.NewPool(),
 			StateGen:          stategen.New(db, doublylinkedtree.New()),
+			BlockBuilder:      &builderTest.MockBuilderService{HasConfigured: true},
 		}
 
 		proposerSlashings := make([]*ethpbalpha.ProposerSlashing, params.BeaconConfig().MaxProposerSlashings)
@@ -2379,6 +2380,7 @@ func TestProduceBlindedBlock(t *testing.T) {
 			ExitPool:          voluntaryexits.NewPool(),
 			StateGen:          stategen.New(db, doublylinkedtree.New()),
 			SyncCommitteePool: synccommittee.NewStore(),
+			BlockBuilder:      &builderTest.MockBuilderService{HasConfigured: true},
 		}
 
 		proposerSlashings := make([]*ethpbalpha.ProposerSlashing, params.BeaconConfig().MaxProposerSlashings)
@@ -2918,7 +2920,7 @@ func TestProduceBlindedBlock(t *testing.T) {
 		assert.DeepEqual(t, expectedBits, blk.Body.SyncAggregate.SyncCommitteeBits)
 		assert.DeepEqual(t, aggregatedSig, blk.Body.SyncAggregate.SyncCommitteeSignature)
 	})
-	t.Run("Unsupported Block Type", func(t *testing.T) {
+	t.Run("full block", func(t *testing.T) {
 		db := dbutil.SetupDB(t)
 		ctx := context.Background()
 
@@ -3054,7 +3056,7 @@ func TestProduceBlindedBlock(t *testing.T) {
 			SyncCommitteePool:      synccommittee.NewStore(),
 			ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache(),
 			BlockBuilder: &builderTest.MockBuilderService{
-				HasConfigured: false,
+				HasConfigured: true,
 			},
 		}
 
@@ -3072,7 +3074,14 @@ func TestProduceBlindedBlock(t *testing.T) {
 			Graffiti:     graffiti[:],
 		}
 		_, err = v1Server.ProduceBlindedBlock(ctx, req)
-		require.ErrorContains(t, " block was not a supported blinded block type", err)
+		require.ErrorContains(t, "Prepared beacon block is not blinded", err)
+	})
+	t.Run("builder not configured", func(t *testing.T) {
+		v1Server := &Server{
+			V1Alpha1Server: &v1alpha1validator.Server{BlockBuilder: &builderTest.MockBuilderService{HasConfigured: false}},
+		}
+		_, err := v1Server.ProduceBlindedBlock(context.Background(), nil)
+		require.ErrorContains(t, "Block builder not configured", err)
 	})
 }
 
@@ -3902,6 +3911,7 @@ func TestProduceBlindedBlock_SyncNotReady(t *testing.T) {
 		HeadFetcher:           chainService,
 		TimeFetcher:           chainService,
 		OptimisticModeFetcher: chainService,
+		V1Alpha1Server:        &v1alpha1validator.Server{BlockBuilder: &builderTest.MockBuilderService{HasConfigured: true}},
 	}
 	_, err = vs.ProduceBlindedBlock(context.Background(), &ethpbv1.ProduceBlockRequest{})
 	assert.ErrorContains(t, "Syncing to latest head, not ready to respond", err)