Could not lock IndexWriter – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch is unable to obtain a lock on the IndexWriter. This usually happens if another instance of IndexWriter is already open or if there’s a problem with the file system permissions. To resolve this issue, ensure that no other processes are using the index. If the problem persists, check the file system permissions to ensure that OpenSearch has the necessary access rights. Also, consider checking for any underlying issues with the storage system, such as disk space or hardware issues.

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This guide will help you check for common problems that cause the log ” could not lock IndexWriter ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: index.

Log Context

Log “could not lock IndexWriter” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

    private IndexWriter createWriter() throws IOException {
        try {
            final IndexWriterConfig iwc = getIndexWriterConfig();
            return createWriter(; iwc);
        } catch (LockObtainFailedException ex) {
            logger.warn("could not lock IndexWriter"; ex);
            throw ex;

    // pkg-private for testing


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