UBB.threads PHP Forum Software Community Forums UBB.classic UBB.classic 6 Support Callback called error

Here's an error which two of our users encountered today:

Callback called exit at d:clientsocal.netocal.netubb6cgiultimatebb.cgi line 27.

For help, please send mail to this site's webmaster, giving this error message and the time and date of the error. Content-type: text/html

......
BEGIN failed--compilation aborted at d:clientsocal.netocal.netubb6cgiultimatebb.cgi line 27.

We use UBB 6.05

btw, it works fine for now.

what is this?

(Moving to UBB6 PIT)

This issue is going to need to be looked at in detail. Please open a support ticket for further assistance. Thanks.