So, you won't be able to just update the version to RC1-1 and expect everything to work - some configuration has changed and some of the method signatures have changed too.
The easiest thing to do is start from a fresh workspace. It's inconvenient, but we're much more stabile now and do not expect any more large changes for 2.0.
If that's not feasible for you, you'll have to dig into the changes. These are some of the things involved (this list is not necessarily comprehensive)
- Remove all references to the hidden input with blc:csrf.. In it
- Change all <form> to <blc:form>. If you don't want a form CSRF secured, you need to specify method="GET"
- Search facet data structure is new – see the load catalog sql file for the new structure
- Embedded / standalone solr config. Configured via the properties files now. Putting this in your common.properties should take care of it: solr.source=solrEmbedded