@Gaoxin_Dai , in general we do not recommend storing large objects in the workflow history, this not only may hit some limits like the one you see here with gRPC, but also has performance implications slowing down history replay, queries and increasing memory footprint of your workers due to growing cache size. It is preferred to save a pointer to the blob in your workflow and put actual object in the blob store, such as S3. Is that an option in your case?