So the "search" add-on is "Missing from disk". That's probably because it was REMOVED from Moodle recently (version 2.3 or 2.4, I think...) It was a buggy "experimental" function that apparently didn't work very well. It's currently being rewritten...
So, restore your origional pre-upgrade 2.3 site from your backup. Then go to Site administration / Plugins / Activity modules / Manage activities. Is there a "search" option there? If so, click DELETE to remove it from your Moodle database (since the code is already gone).
Once it's gone try the upgrade again. It should hopfully be able to get past this problem now.