I got this message on log in today:

"Level up failed for enigma in class 13"

Not that it hindered play or anything.

Does that ring a bell to anyone?

Does for me!

Don't have this problem, but 'class 13', is, in alphabetical order (as the classes are, but in two lists: One for regular one for prestige) is Arcane Archer, so I assume that someone tried to get a arcane archer level.

I had a similar log message yesterday, it mentioned someone else but the "class 13" bit was there.

Quite strange

I think this is something to do with certain folk's somethings. Shouldn't worry, I don't think!

I got another one last night,

"Level up failed for Jimmy in class 13"

any idea what these are from?

'Enigma' is the name of my personal animatron servant. I get this message whenever I add it back into my party by getting it to follow me.

Why others get this message I am not sure. And not either why it occurs in the first place. This thing only has "Construct" levels. So it should not concern you in any way.