Which version of Prince are you running, on which distro, which package is installed, and how is Prince being invoked? (e.g. through one of the wrappers, from the shell, what is the parent process?)
I am running it with Pressbooks. It used to run well. But after a system update it stopped running. It is still working when I execute the command with CLI. I suspect some permission issue, but I just cannot find it. I posted it here in case somebody else had the same issue and rembemers solution.
We have had signals issues under PHP some years ago but they were already fixed, can you check which version of Ubuntu, the webserver (Apache?) and the PHP version and how it is being run (Apache module?) as this will help us to reproduce the problem.
I don't think the wrapper is affecting the behaviour of signals, perhaps there is an issue on FreeBSD we have not encountered before, we will investigate.
The following command is successful when using it with CLI. Using proc_open from php wrapper leads to the error: Signals delivery constantly fails at GC #1
We have found that there is a known signals issue with Boehm GC when running on FreeBSD, so we will create an updated Prince build next week and see if this fixes the problem.
