Solr Synonyms after deleting also not deleted from server and resulting in full-indexing fail UPDATE

[Former Member]

I had the same error as mentioned in ticket https://answers.sap.com/questions/12939795/solr-synonyms-after-deleting-also-not-deleted-from.html.

However this thread is already closed and I found the answers a bit unspecific and therefore unsatisfying.

In my case, the problem was that there were two synonyms with the same "synonymFrom" value but with different uppercase/lowercase writings e.g.: "test" and "Test".

During the indexing process SOLR fetches all synonyms from the server and iterates over them in order to send an individual delete command for every one of them.

However when the delete statement for "test" is sent to the server both "test" and "Test" are removed. When hybris tries to delete "Test" this synonym already has been removed.

My solution was to merge all the "to" values of the affected synonyms into the lowercase variant.