I have been given the task of upgrading our Crucible/Fisheye instance and we are at version 2.4.2 and I want to go to the 2.7 release and no, we do no have a test instance :(
Is it safe to skip the 2.5 and 2.6 versions since I noticed those versions do make changes to the metadata?
It shouldn't be a problem - see http://confluence.atlassian.com/display/FISHEYE/FishEye+Upgrade+Guide
A few things to watch out for:
In FishEye 3.0 we've dropped support for Postgres 8 and MySql 5.0 - It's a good idea not to use either of these for 2.7 as well.
If you're using JIRA for user management, then the process wil take a long time due to resync.
As always, please ensure you take a full-backup of the FishEye data directory before attempting to upgrade.
There are some upgrade tasks, which will force a re-index of each repository (not a full re-index, however a re-index of some of the lucene indexes none the same) so you will notice some repositories will not be immediately available. Depending on your repository size, and the number of repos you have, these should be finished within a few hours max however.