🇧🇪Belgium @pieterjandp

Drupal 9 compatibility has been implemented in #3116464: Drupal 9 Readiness →

I had the same issue. It is impossible to update the settings of an "open" existing Elasticsearch index, so it is not possible to add additional analyzers or update mappings.

Everything worked fine after deleting and recreating the index (and unfortunately the views using this index as well).