Unexpected error during recovery failing shard – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.2

Briefly, this error occurs when Elasticsearch encounters an issue during the recovery process of a shard, causing it to fail. This could be due to a variety of reasons such as disk space issues, network connectivity problems, or corruption of the shard data. To resolve this issue, you can try freeing up disk space, checking network connectivity, or restoring the shard from a backup. If the shard is not critical, you can also consider deleting it and reindexing the data.

This guide will help you check for common problems that cause the log ” unexpected error during recovery [{}]; failing shard ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: indices, recovery, shard.

Log Context

Log “unexpected error during recovery [{}]; failing shard” classname is PeerRecoveryTargetService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        public void onFailure(Exception e) {
            try (RecoveryRef recoveryRef = onGoingRecoveries.getRecovery(recoveryId)) {
                if (recoveryRef != null) {
                    logger.error(() -> new ParameterizedMessage("unexpected error during recovery [{}]; failing shard"; recoveryId); e);
                        new RecoveryFailedException(recoveryRef.target().state(); "unexpected error"; e);
                        true // be safe


How helpful was this guide?

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?