diff --git a/packages/kbn-apm-synthtrace-client/src/lib/otel/error.ts b/packages/kbn-apm-synthtrace-client/src/lib/otel/error.ts
index 63265d45fe886..1ea9f8172d4c9 100644
--- a/packages/kbn-apm-synthtrace-client/src/lib/otel/error.ts
+++ b/packages/kbn-apm-synthtrace-client/src/lib/otel/error.ts
@@ -21,6 +21,7 @@ export interface OtelErrorDocument extends OtelDocument {
     'timestamp.us'?: number;
     'event.name'?: string;
     'error.id'?: string;
+    'error.grouping_key'?: string;
   };
 }