I use xenforo 1.0.2 on an english forum.
Other addons I have installed: nearly all of Jaxels addons, XFr Board Notices, LN Blog, taiga chat and minorin, mass alert, bb code manager, and a few minor addons.
I installed the addon by uploading all the files, and installing the xml by typing in the address in my browser ./library etc.
The error occurred when creating any error type (bug or task) in a project in a category. Ive created bugs/tasks with different options in them (milestones, versions etc) and the same error always occurs.