Unexpected failure while failing primary – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.17-8.2

Briefly, this error occurs when Elasticsearch encounters an issue while trying to mark a primary shard as failed. This could be due to network issues, disk space problems, or a bug in the Elasticsearch software. To resolve this issue, you can try to restart the Elasticsearch node, check for network connectivity issues, ensure there is enough disk space, or upgrade Elasticsearch to the latest version to fix potential bugs.

This guide will help you check for common problems that cause the log ” unexpected failure while failing primary [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: replication.

Log Context

Log “unexpected failure while failing primary [{}]” classname is ReplicationOperation.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                public void onFailure(Exception e) {
                    assert false : e;
                    logger.error(new ParameterizedMessage("unexpected failure while failing primary [{}]"; primary.routingEntry()); e);
                        new RetryOnPrimaryException(
                            String.format(Locale.ROOT; "unexpected failure while failing primary [%s]"; primary.routingEntry());


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