Lock assertion failed – 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 acquire a lock on a file or directory it needs to access. This could be due to insufficient permissions, another process using the file, or a file system issue. To resolve this, you can check and adjust the file or directory permissions, ensure no other processes are using the file, or investigate potential file system issues. If the error persists, restarting the OpenSearch service may help.

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This guide will help you check for common problems that cause the log ” lock assertion failed ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: .

Log Context

Log “lock assertion failed” classname is NodeEnvironment.java.
We extracted the following from OpenSearch source code for those seeking an in-depth context :

        if (!closed.get() && locks != null) {
            for (Lock lock : locks) {
                try {
                } catch (IOException e) {
                    logger.warn("lock assertion failed"; e);
                    throw new IllegalStateException("environment is not locked"; e);


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