Could not lock IndexWriter isLocked – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 2.3-2.3

Briefly, this error occurs when Elasticsearch is unable to obtain a lock on the IndexWriter, which is necessary for writing data to an index. This could be due to multiple instances of IndexWriter trying to write to the same index concurrently, or a previous instance not releasing the lock properly. To resolve this issue, ensure only one instance of IndexWriter is running at a time, or manually release the lock if it’s held by a terminated process. Also, check for any underlying issues like disk space or permissions that might prevent Elasticsearch from acquiring the lock.

This guide will help you check for common problems that cause the log ” Could not lock IndexWriter isLocked [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

Log “Could not lock IndexWriter isLocked [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            return new IndexWriter(; iwc);
        } catch (LockObtainFailedException ex) {
            boolean isLocked = IndexWriter.isLocked(;
            logger.warn("Could not lock IndexWriter isLocked [{}]"; ex; isLocked);
            throw ex;

    /** Extended SearcherFactory that warms the segments if needed when acquiring a new searcher */


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