Removing read only block on because reindex failed – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.16-8.9

Briefly, this error occurs when Elasticsearch tries to remove a read-only block due to a failed reindex operation. This could be due to insufficient disk space, incorrect index settings, or network issues. To resolve this, you can free up disk space, check and correct your index settings, or troubleshoot your network. Additionally, ensure that your Elasticsearch cluster has enough resources to handle the reindex operation.

This guide will help you check for common problems that cause the log ” removing read only block on [{}] because reindex failed [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: reindex.

Log Context

Log “removing read only block on [{}] because reindex failed [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        migrationInfo.createClient(baseClient).execute(ReindexAction.INSTANCE; reindexRequest; listener);

    // Failure handlers
    private void removeReadOnlyBlockOnReindexFailure(Index index; ActionListener listener; Exception ex) {"removing read only block on [{}] because reindex failed [{}]"; index; ex);
        setWriteBlock(index; false; ActionListener.wrap(unsetReadOnlyResponse -> listener.onFailure(ex); e1 -> listener.onFailure(ex)));

    private static ElasticsearchException logAndThrowExceptionForFailures(BulkByScrollResponse bulkByScrollResponse) {
        String bulkFailures = (bulkByScrollResponse.getBulkFailures() != null)