Briefly, this error occurs when Elasticsearch expects a version string for the [min_version] parameter, but it’s not provided or is in an incorrect format. This usually happens during operations like index creation or upgrade. To resolve this, ensure that the [min_version] parameter is correctly specified in the request. It should be a string representing the minimum version of Elasticsearch required for the operation. Also, check for any syntax errors or typos in your request.
This guide will help you check for common problems that cause the log ” version string expected [min_version] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: repositories, version.
Overview
An Elasticsearch snapshot provides a backup mechanism that takes the current state and data in the cluster and saves it to a repository (read snapshot for more information). The backup process requires a repository to be created first. The repository needs to be registered using the _snapshot endpoint, and multiple repositories can be created per cluster. The following repository types are supported:
Repository types
| Repository type | Configuration type |
|---|---|
| Shared file system | Type: “fs” |
| S3 | Type : “s3” |
| HDFS | Type :“hdfs” |
| Azure | Type: “azure” |
| Google Cloud Storage | Type : “gcs” |
Examples
To register an “fs” repository:
PUT _snapshot/my_repo_01
{
"type": "fs",
"settings": {
"location": "/mnt/my_repo_dir"
}
}Notes and good things to know
- S3, HDFS, Azure and Google Cloud require a relevant plugin to be installed before it can be used for a snapshot.
- The setting, path.repo: /mnt/my_repo_dir needs to be added to elasticsearch.yml on all the nodes if you are planning to use the repo type of file system. Otherwise, it will fail.
- When using remote repositories, the network bandwidth and repository storage throughput should be high enough to complete the snapshot operations normally, otherwise you will end up with partial snapshots.
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
}Log Context
Log “version string expected [min_version]” class name is RepositoryData.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
throw new ElasticsearchParseException("start object expected [" + INDEX_METADATA_IDENTIFIERS + "]");
}
indexMetaIdentifiers.putAll(parser.mapStrings());
} else if (MIN_VERSION.equals(field)) {
if (parser.nextToken() != XContentParser.Token.VALUE_STRING) {
throw new ElasticsearchParseException("version string expected [min_version]");
}
final Version version = Version.fromString(parser.text());
assert SnapshotsService.useShardGenerations(version);
} else {
throw new ElasticsearchParseException("unknown field name [" + field + "]");
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