That’s what I get for toying with stuff I should leave alone… I tried to merge the articles from my other Joomla installation back into my main site. After clicking around for a bit it seemed like the manual database merge worked out.
Next I found a number of modules with version number 1.0.x – assuming these were remains of the original 1.0.x installation I selected them all and hit delete. On the page refresh I noticed something was off… The menu was gone! Most of the Joomla Administrator panel was working but without a menu, a lot of sections are unavailable…
After installing a second installation over the existing one I managed to get the missing modules back (note to self: make sure to download the full package AND copy all the files…) by copying tables between the 2 installations. Finally I had a working installation again but now the other users (a.k.a not me) did not show up anymore…
After Googling for weeks I finally found a thread in which somebody made a whole database schema for Joomla! 1.5. The schema can be found here.
Even though I had restored most of the key references within Joomla! I somehow missed the ‘jos_core_acl_groups_aro_maps’ table – this only had one entry: for admin only. As soon as I realized my mistake, I manually added the missing rows and everything started working properly again.
Note to self: stop breaking the site…