invalid_index_name_exception: invalid_index_name_exception

What does it mean?

The given index name does not follow Elasticsearch naming rules. The name contains invalid characters or violates format rules.

Why does it happen?

Uppercase letters, disallowed characters (\ / * ? " < > | space , #), a name starting with _, - or +, a name that is too long (over 255 bytes), or reserved names such as . / ... (Names starting with a dot are not forbidden but are reserved for hidden/system indices and produce a warning.)

How to fix it

Make the index name compliant: use lowercase only; avoid forbidden characters; do not start the name with _, - or +, and do not use names starting with a dot except for system/hidden indices. Keep the name under 255 bytes. Enforce these rules in the application when generating index names.