Briefly, this error occurs when the destination index name in Elasticsearch is not in lowercase. Elasticsearch requires all index names to be in lowercase. This is a built-in validation to prevent issues that could arise from case-sensitive index names. To resolve this issue, you should rename your index to a lowercase name. You can do this by reindexing your data into a new index with a lowercase name, or by creating an alias with a lowercase name that points to your existing index.
This guide will help you check for common problems that cause the log ” dest.index must be lowercase ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.
Log Context
Log “dest.index must be lowercase” class name is DataFrameAnalyticsDest.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
public void validate() {
if (index != null) {
validateIndexOrAliasName(index; InvalidIndexNameException::new);
if (index.toLowerCase(Locale.ROOT).equals(index) == false) {
throw new InvalidIndexNameException(index; "dest.index must be lowercase");
}
}
}
}
