We have just upgraded to Apache 2.4 from 2.2 and our fastcgi apps are now causing the error message 'End of script output before headers'.
All the apps and libraries, which are all in C, have been recompiled using the latest libraries from fastcgi.com and they worked fine before the upgrade.
Any clues as to the cause of the problem would be appreciated.
The server is Fedora 19
As it turned out the problem was with a shared object file that wasn't of the correct version. For some odd reason that error did not show in the log.
So, question should be closed.