Error when opening compound reader for Directory and – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-1.1

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Briefly, this error occurs when OpenSearch is unable to access the index files due to issues with the directory or file system. This could be due to insufficient permissions, corrupted files, or disk space issues. To resolve this, you can check and correct the file permissions, verify the integrity of the index files, or ensure there is enough disk space. If the files are corrupted, you may need to restore from a backup. Also, consider checking the health of your hardware as faulty hardware can cause such issues.

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This guide will help you check for common problems that cause the log ” Error when opening compound reader for Directory [{}] and ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: index.

Log Context

Log “Error when opening compound reader for Directory [{}] and” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

        if (useCompoundFile) {
            try {
                directory = engineConfig.getCodec().compoundFormat().getCompoundReader(;
          ; IOContext.READ);
            } catch (IOException e) {
                logger.warn(() -> new ParameterizedMessage("Error when opening compound reader for Directory [{}] and " +
                    "SegmentCommitInfo [{}]";; segmentCommitInfo); e);

                return ImmutableOpenMap.of();
        } else {


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