%s unable to prewarm file %s – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.3-8.9

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Briefly, this error occurs when Elasticsearch tries to load data into the cache before it’s needed (prewarming) but fails, usually due to insufficient disk space or permissions issues. To resolve this, you can free up disk space, check and adjust file permissions, or disable prewarming by setting “index.store.preload” to “none” in the Elasticsearch configuration file. However, disabling prewarming might impact performance.

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This guide will help you check for common problems that cause the log ” %s unable to prewarm file [%s] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “%s unable to prewarm file [%s]” classname is SearchableSnapshotDirectory.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                } catch (Exception e) {
                    logger.warn(() -> format("%s unable to prewarm file [%s]"; shardId; file.physicalName()); e);


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