This is a major step because solr removed support for embedded solr
instances in 9.0 and we want to keep it because we want to ship
YaCy with an embedded solr. It was necessary to add parts of solr
code into YaCy to make this migration possible. Further on with
Solr 9.1 they removed even more parts which are required for embedded
operation, therefore we cannot migrate yet further without big
changes.
If you are running a YaCy instance with Solr 8.x, the migration should
be done automatically. If not you require to first migrate to a YaCy
version 1.93 with Solr 8.x to migrate to Solr 8 data.
Michael Peter Christen
8eb0d490aa