Seed read from master dat was – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.4-7.13

Briefly, this error occurs when Elasticsearch encounters an issue while reading the seed from the master.dat file. This could be due to corruption of the file, incorrect file permissions, or disk space issues. To resolve this, you can try restoring the master.dat file from a backup, checking and correcting file permissions, or freeing up disk space. If the issue persists, consider reindexing your data into a new Elasticsearch cluster.

This guide will help you check for common problems that cause the log ” Seed read from master.dat was [ ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: repositories, master, blobstore.

Log Context

Log “Seed read from master.dat was [” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 "] is not accessible on the node [" + localNode + "]"; exp);
 try (InputStream masterDat = testBlobContainer.readBlob("master.dat")) {
 final String seedRead = Streams.readFully(masterDat).utf8ToString();
 if (seedRead.equals(seed) == false) {
 throw new RepositoryVerificationException(; "Seed read from master.dat was [" + seedRead +
 "] but expected seed [" + seed + "]");
 } catch (NoSuchFileException e) {
 throw new RepositoryVerificationException(; "a file written by master to the store [" + blobStore() +
 "] cannot be accessed on the node [" + localNode + "]. " +


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