Failed to acquire searcher source – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-7.9

Briefly, this error occurs when Elasticsearch is unable to obtain the searcher source, which is essential for executing search operations. This could be due to a variety of reasons such as insufficient resources, heavy indexing, or a corrupted index. To resolve this issue, you can try the following: 1) Increase the resources of your Elasticsearch cluster, 2) Reduce the indexing load if it’s too high, 3) Check for corrupted indices and repair or delete them, and 4) Ensure that your Elasticsearch version is up-to-date and free of known bugs.

This guide will help you check for common problems that cause the log ” failed to acquire searcher; source {} ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index, source.

Log Context

Log “failed to acquire searcher; source {}” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        } catch (AlreadyClosedException ex) {
            throw ex;
        } catch (Exception ex) {
            maybeFailEngine("acquire_searcher"; ex);
            ensureOpen(ex); // throw EngineCloseException here if we are already closed
            logger.error(() -> new ParameterizedMessage("failed to acquire searcher; source {}"; source); ex);
            throw new EngineException(shardId; "failed to acquire searcher; source " + source; ex);
        } finally {


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