Briefly, this error occurs when Elasticsearch is unable to verify the version of the snapshot during a restore operation. This could be due to a mismatch between the snapshot version and the Elasticsearch cluster version. To resolve this issue, you can either upgrade your Elasticsearch cluster to match the snapshot version or downgrade the snapshot version to match the cluster. Alternatively, you can create a new snapshot from a cluster with a compatible version. Always ensure that the snapshot and cluster versions are compatible before initiating a restore operation.
This guide will help you check for common problems that cause the log ” [{}] Failed verifying snapshot version ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: version, task, plugin, snapshot.
Overview
A version corresponds to the Elasticsearch built-in tracking system that tracks the changes in each document’s update. When a document is indexed for the first time, it is assigned a version 1 using _version key. When the same document gets a subsequent update, the _version is incremented by 1 with every index, update or delete API call.
What it is used for
A version is used to handle the concurrency issues in Elasticsearch which come into play during simultaneous accessing of an index by multiple users. Elasticsearch handles this issue with an optimistic locking concept using the _version parameter to avoid letting multiple users edit the same document at the same time and protects users from generating incorrect data.
Notes
You cannot see the history of the document using _version. That means Elasticsearch does not use _version to keep a track of original changes that had been performed on the document. For example, if a document has been updated 10 times, it’s _version would be marked by Elasticsearch as 11, but you cannot go back and see what version 5 of the document looked like. This has to be implemented independently.
Common problems
If optimistic locking is not implemented while making updates to a document, Elasticsearch may return a conflict error with the 409 status code, which means that multiple users are trying to update the same version of the document at the same time.
POST /ratings/123?version=50
{
"name": "Joker",
"rating": 50
}Overview
A task is an Elasticsearch operation, which can be any request performed on an Elasticsearch cluster, such as a delete by query request, a search request and so on. Elasticsearch provides a dedicated Task API for the task management which includes various actions, from retrieving the status of current running tasks to canceling any long running task.
Examples
Get all currently running tasks on all nodes of the cluster
Apart from other information, the response of the below request contains task IDs of all the tasks which can be used to get detailed information about the particular task in question.
GET _tasks
Get detailed information of a particular task
Where clQFAL_VRrmnlRyPsu_p8A:1132678759 is the ID of the task in below request
GET _tasks/clQFAL_VRrmnlRyPsu_p8A:1132678759
Get all the current tasks running on particular nodes
GET _tasks?nodes=nodeId1,nodeId2
Cancel a task
Where clQFAL_VRrmnlRyPsu_p8A:1132678759 is the ID of the task in the below request
POST /_tasks/clQFAL_VRrmnlRyPsu_p8A:1132678759/_cancel?pretty
Notes
- The Task API will be most useful when you want to investigate the spike of resource utilization in the cluster or want to cancel an operation.
Log Context
Log “[{}] Failed verifying snapshot version” classname is OpenJobPersistentTasksExecutor.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
}
})
);
e -> {
if (autodetectProcessManager.isNodeDying() == false) {
logger.error(new ParameterizedMessage("[{}] Failed verifying snapshot version"; params.getJobId()); e);
failTask(jobTask; "failed snapshot verification; cause: " + e.getMessage());
}
}
);
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