Where is this error function?

[somerfeld]

I'm developing a hack however I cant seem to find where I get this message from. Can someone please tell me where this functio is located. kudos in advance

No forum specified. If you followed a valid link, please notify the webmaster

[Admin]

This happens when you try to do something which requires a forumid but it's not set.
This is really all over the place, can you be more specific?