XF 2.2 Error: Key 'thread_id_post_date' doesn't exist


I wanted to delete a few postings in a thread this morning, but when trying with the last post I received an error message.

Then rebuilding of cache of the threads gave me the same error now:
XF\Db\InvalidQueryException: MySQL statement prepare error [1176]: Key 'thread_id_post_date' doesn't exist in table 'xf_post' in src/XF/Db/AbstractStatement.php at line 230.

I checked and this field does not even exist in my 'xf_post'-table.

Using latest version, everything up to date and posting new messages does seem to work normal.