Elasticsearch Restore from S3 Snapshot

Question

We are trying to Restore the snapshot from S3 bucket. The snapshot is taken from a different cluster (7.12) & getting restored in different cluster (7.17 ).

Below is the error during the restore activity

"error":{"root_cause":[{"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (add-block-index-to-close [[cib_/MAZVfK1fR2aQL2op_bMAhg]]) within 30s"}],"type":"process_cluster_event_timeout_exception","reason":"failed to process cluster event (add-block-index-to-close [[cib_/MAZVfK1fR2aQL2op_bMAhg]]) within 30s"},"status":503}

We are using an automation script to close the index & perform restore using below statements

curl -X POST -u admin:$passw "https://$HOST_NAME:9201/$index/_close"

      curl -X POST -u admin:$passw "https://$HOST_NAME:9201/_snapshot/$REPOSITORY_NAME/$snapshotname/_restore?wait_for_completion=true" -H 'Content-Type:application/json' -d'
     {
      "indices": "'"$index"'",
      "ignore_unavailable": true,
      "include_global_state": false,
      "partial": false,
      "index_settings":{
      "index.routing.allocation.exclude.app": "someapp"
                       }
       }
      ' >> s3repo_cibrcdn.json 

Can someone help about the error. We dont have any timeouts mentioned