diff --git a/packages/beacon-node/src/api/impl/validator/index.ts b/packages/beacon-node/src/api/impl/validator/index.ts
index 658c86b905ff..3b21b4434f1d 100644
--- a/packages/beacon-node/src/api/impl/validator/index.ts
+++ b/packages/beacon-node/src/api/impl/validator/index.ts
@@ -1067,7 +1067,13 @@ export function getValidatorApi({
 
       await waitForSlot(slot); // Must never request for a future slot > currentSlot
 
-      const aggregate = chain.attestationPool.getAggregate(slot, attestationDataRoot);
+      const dataRootHex = toHexString(attestationDataRoot);
+      const aggregate = chain.attestationPool.getAggregate(slot, dataRootHex);
+
+      if (!aggregate) {
+        throw new ApiError(404, `No aggregated attestation for slot=${slot}, dataRoot=${dataRootHex}`);
+      }
+
       metrics?.production.producedAggregateParticipants.observe(aggregate.aggregationBits.getTrueBitIndexes().length);
 
       return {
diff --git a/packages/beacon-node/src/chain/opPools/attestationPool.ts b/packages/beacon-node/src/chain/opPools/attestationPool.ts
index a04cd7592091..804d8798cbc2 100644
--- a/packages/beacon-node/src/chain/opPools/attestationPool.ts
+++ b/packages/beacon-node/src/chain/opPools/attestationPool.ts
@@ -1,7 +1,7 @@
 import {PointFormat, Signature} from "@chainsafe/bls/types";
 import bls from "@chainsafe/bls";
-import {BitArray, toHexString} from "@chainsafe/ssz";
-import {phase0, Slot, Root, RootHex} from "@lodestar/types";
+import {BitArray} from "@chainsafe/ssz";
+import {phase0, Slot, RootHex} from "@lodestar/types";
 import {MapDef} from "@lodestar/utils";
 import {IClock} from "../../util/clock.js";
 import {InsertOutcome, OpPoolError, OpPoolErrorCode} from "./types.js";
@@ -128,12 +128,11 @@ export class AttestationPool {
   /**
    * For validator API to get an aggregate
    */
-  getAggregate(slot: Slot, dataRoot: Root): phase0.Attestation {
-    const dataRootHex = toHexString(dataRoot);
+  getAggregate(slot: Slot, dataRootHex: RootHex): phase0.Attestation | null {
     const aggregate = this.attestationByRootBySlot.get(slot)?.get(dataRootHex);
     if (!aggregate) {
       // TODO: Add metric for missing aggregates
-      throw Error(`No attestation for slot=${slot} dataRoot=${dataRootHex}`);
+      return null;
     }
 
     return fastToAttestation(aggregate);