Briefly, this error occurs when you try to modify certain settings during the restore process of an Elasticsearch snapshot. Some settings are not modifiable during a restore operation. To resolve this issue, you can either modify the settings before or after the restore process. Alternatively, you can exclude these settings from the restore operation. It’s important to understand which settings are modifiable during a restore to avoid such errors.
This guide will help you check for common problems that cause the log ” cannot modify setting [” + k + “] on restore ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: restore.
Overview
In Elasticsearch, restore refers to the snapshot restore mechanism, which returns indices or clusters to a previous, saved state. You can restore the entire cluster from the snapshot or restore an individual index or selected indices.
Examples
To restore the whole snapshot:
POST /_snapshot/my_backup/snapshot-01-11-2019/_restore
To restore an individual index:
POST /_snapshot/my_backup/snapshot-01-11-2019/_restore
{
"indices": "my_index"
}Notes
- If you are using a security tool like Searchguard, the snapshot restore capability must be enabled in elasticsearch.yml. Otherwise, it will throw a security exception.
Common issues
- If an index or indices already exist with the same names as those you are going to restore, they need to either be closed or deleted before you can restore from a snapshot. Otherwise, the restore operation will fail due to an error that the index already exists.
Log Context
Log “cannot modify setting [” + k + “] on restore” class name is RestoreService.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
}
}
return true;
})).put(normalizedChangeSettings.filter(k -> {
if (UNMODIFIABLE_SETTINGS.contains(k)) {
throw new SnapshotRestoreException(snapshot; "cannot modify setting [" + k + "] on restore");
} else {
return true;
}
}));
settingsBuilder.remove(MetadataIndexStateService.VERIFIED_BEFORE_CLOSE_SETTING.getKey());
