My upgrade to 1.25 seemed to work, but in fact not. Here is the last error message:
Fatal error: Call to undefined method Title::userCanRead() in [...]/includes/Wiki.php on line 158
It might have something to do with a missing extension, for I removed a lot of them to simplify first.
Thanks in advance for any hint.
Wiki.php should not exist in MediaWiki 1.25 so apparently you did not follow the steps in Manual:Upgrading, specifically the warnings about extracting new files on a new, empty directory and not over the old installation.
OK, thanks. I restarted the whole process from scratch. There was another error, for the data base is used by some others tools (blog, in particular), so the fields for Mediawiki have a specific prefix.
Now, at least, the wiki part begins to run. A lot of things are not well displayed, and I am now in the process of slowly adding all the needed extensions.
