Hi, to be sure it is not a Solr version issue you could try reinstalling the exact same YaCy version you used before Debian reinstall.
But to my mind, looking at your error stack and at involved Solr sources it is more probably a consistency issue with one of your index file. YaCy might have incorrectly stopped and let a Solr file in a corrupted state...
I don't think recovering your index data is desperate. Maybe can you try following a procedure such as described here : Solr fix corrupted index
Let us now if you have some success, it may be quite useful!