Cancelling replications for allocationIds – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 2.7-2.9

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Briefly, this error occurs when OpenSearch decides to cancel ongoing shard replication due to changes in the allocation of shards. This could be due to nodes leaving or joining the cluster, or due to manual reallocation. To resolve this issue, ensure that your cluster is stable with no nodes unexpectedly leaving or joining. If you’re manually reallocating shards, ensure that you’re doing so correctly. Also, check your cluster’s health and logs for any underlying issues that might be causing instability.

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This guide will help you check for common problems that cause the log ” Cancelling replications for allocationIds {} ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: allocation, indices, replication.

Log Context

Log “Cancelling replications for allocationIds {}” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

        if (allocationIds.size() == 0) {
        logger.warn(() -> new ParameterizedMessage("Cancelling replications for allocationIds {}"; allocationIds));
        for (String allocationId : allocationIds) {
            cancel(allocationId; reason);


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