I still have one server running 5.0.12. I'd never upgraded it to 5.0.13a because I don't seem to have the 5.0.13 QMR, although I have 5.0.13a, and AFAIK I'd have to apply 5.0.13 before 5.0.13a.
Can anyone confirm whether this is correct? Or was there no 5.0.13 QMR? Or can I just apply the 5.0.13a QMR over 5.0.12?
It's ancient history, but I might as well apply the QMR if I can. . .

