"ErrorException: Elasticsearch index must be rebuilt to include custom mappings."

[nocte]

Immediately after upgrading from 3.3.1 to 3.3.2 I found this error in the XF error log:

ErrorException: Elasticsearch index must be rebuilt to include custom mappings. src/XF/Error.php:75
Generated by: admin Apr 23, 2020 at 10:45 PM

According to the change log, there were only smaller adjustments done:

ElasticSearch Essentials 3.3.2

atelieraphelion.com

What is the reason for this error? I cannot remember to have seen that error before..

 

[Xon]

This indicates your elasticsearch index has a type mapping which doesn't match what XenForo expects. If you go to the Settings => Elastic search page, there is a new section "Elastic Search Type mappings".

It should look something like this, but with some lines in red because they don't match;