Prewarming failed for file – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.13-8.2

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Briefly, this error occurs when Elasticsearch tries to load data into the cache before it’s needed (prewarming), but fails due to issues like insufficient memory, incorrect file path, or file corruption. To resolve this, you can increase the heap size to provide more memory, ensure the file path is correct and accessible, or check the file for corruption and replace it if necessary. Also, consider disabling prewarming if it’s not essential for your use case.

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

Log Context

Log “{} prewarming failed for file [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                fileCompletionListener.addListener( -> null));
                fileCompletionListener.whenComplete(voids -> {
                    logger.debug("{} file [{}] prewarmed"; shardId; file.physicalName());
                }; e -> {
                    logger.warn(() -> new ParameterizedMessage("{} prewarming failed for file [{}]"; shardId; file.physicalName()); e);

                final GroupedActionListener partsListener = new GroupedActionListener(fileCompletionListener; numberOfParts);
                submitted = true;


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