Briefly, this error occurs when Elasticsearch encounters forbidden characters in the index name, document id, or field name. Elasticsearch has a set of characters that are not allowed in these identifiers. The error message usually specifies which characters are causing the issue. To resolve this, you should rename the index, document id, or field name to exclude these characters. If the forbidden characters are being generated automatically, you may need to modify your data ingestion or processing scripts to prevent these characters from being included.
This guide will help you check for common problems that cause the log ” must not contain the following characters ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: repositories.
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.
Log Context
Log “must not contain the following characters” class name is RepositoriesService.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
}
if (repositoryName.contains("#")) {
throw new RepositoryException(repositoryName; "must not contain '#'");
}
if (Strings.validFileName(repositoryName) == false) {
throw new RepositoryException(repositoryName; "must not contain the following characters " + Strings.INVALID_FILENAME_CHARS);
}
} private static void ensureRepositoryNotInUse(ClusterState clusterState; String repository) {
final SnapshotsInProgress snapshots = clusterState.custom(SnapshotsInProgress.TYPE; SnapshotsInProgress.EMPTY);
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