Failed to sample – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-1.3

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Briefly, this error occurs when OpenSearch is unable to collect a sample of data from the index. This could be due to a variety of reasons such as insufficient permissions, network issues, or a problem with the index itself. To resolve this issue, you can try the following: 1) Check and adjust the user permissions to ensure OpenSearch has access to the index. 2) Verify the network connectivity between OpenSearch and the index. 3) Investigate the health of the index and consider reindexing if necessary.

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This guide will help you check for common problems that cause the log ” failed to sample ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: client.

Log Context

Log “failed to sample” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

                if (!closed) {
                    nodesSamplerCancellable = threadPool.schedule(this; nodesSamplerInterval; ThreadPool.Names.GENERIC);
            } catch (Exception e) {
                logger.warn("failed to sample"; e);

    class SimpleNodeSampler extends NodeSampler {


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