Could not read repository data from index blob – How to solve this Elasticsearch error

Opster Team

July-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many configuration errors.

Briefly, this error occurs when Elasticsearch is unable to read the repository data from the index blob in the repository. This could be due to issues with the repository or issues with the data stored in the repository. You will need to resolve the issue to create a successful snapshot.

To easily locate the root cause and resolve this issue try AutoOps for Elasticsearch & OpenSearch. It diagnoses problems by analyzing hundreds of metrics collected by a lightweight agent and offers guidance for resolving them.

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This guide will help you check for common problems that cause the log ” could not read repository data from index blob ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: repositories, repository, blobstore and index.

Log Context

Log “could not read repository data from index blob”classname  is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

// operations must start from the EMPTY_REPO_GEN again
 if (latestKnownRepoGen.compareAndSet(indexGen; RepositoryData.EMPTY_REPO_GEN)) {
 logger.warn("Resetting repository generation tracker because we failed to read generation [" + indexGen + "]"; ioe);
 throw new RepositoryException(; "could not read repository data from index blob"; ioe);
 private static String testBlobPrefix(String seed) {
 return TESTS_FILE + seed;


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