Pebble 2.5 introduces a new plugin system. If you have any custom plugins in pebble, you will need to write a plugin descriptor for them. Instructions on writing a plugin descriptor can be found on the Pebble wiki.
There are no specific upgrade intsructions if you are upgrading from a previous 2.0 version of Pebble (including milestones and release candidates). However, you should be aware that Pebble will perform the following activities the first time you start it up following an upgrade. You should backup your Pebble data directory before upgrading.
- Restructure the directory hierarchy in which blog entries are stored to be GMT based.
- Set your theme back to "default".
- Reset the following plugins back to their default configuration.
- Permalink Provider
- Content Decorators
- Blog Listeners
- Blog Entry Listeners
- Comment Listeners
- Comment Confirmation Strategy
- TrackBack Listeners
- TrackBack Confirmation Strategy
- Lucene Analyzer
Once you are happy that Pebble is working as expected, you should set your theme back to the one you were using prior to the upgrade (via the blog properties page) and customize the plugins as required (via the plugins page).