I’m trying to install PTB on Ubuntu 24.04.1 LTS via NeuroDebian.
I followed the procedure outlined on NeuroDebian, but accidentally did the one for Octave, so I did sudo apt-get remove octave-psychtoolbox-3
and then restarted with sudo apt-get install matlab-psychtoolbox-3
I don’t know if my false start has anything to do with it, but I’m getting the error:
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
matlab-psychtoolbox-3-nonfree : Depends: libgl1-mesa-glx but it is not installable
E: Unable to correct problems, you have held broken packages.
Can anyone suggest a solution?
Joe
I also just tried posting this question to the NeuroDebian Listserve, but it’s not accepting my confirmation code to join the list. I just tried contacting the list owner. This is my first time with NeuroDebian. Are these sorts of problems normal for it?
No, not in general. What happens is that the package libgl1-mesa-glx, which was a transitional deprecated package since years, got finally removed in Ubuntu 24.04, and the matlab-psychtoolbox-3-nonfree package depends on it, so fails to install.
I didn’t notice this during my minimal testing, since my upgrade of my machine from Ubuntu 22.04 to 24.04 did retains the old transitional package from Ubuntu 22.04. Only brand new / fresh installation of Ubuntu 24.04-LTS on a system, instead of upgrade from an older Ubuntu version, will not have this package available at all.
The proper solution will be for NeuroDebian to update their matlab-psychtoolbox-3-nonfree package to no longer depend on the obsolete package libgl1-mesa-glx, but instead on the libgl1 package, just as the octave-psychtoolbox-3 does.
Update: Problem should be fixed by NeuroDebian, no need for the workaround anymore.
As a workaround until this is fixed in NeuroDebian, do this:
- Go to http://archive.ubuntu.com/ubuntu/pool/universe/m/mesa/libgl1-mesa-glx_22.0.1-1ubuntu2_amd64.deb this will download the missing package to your Downloads folder.
- Install it from a terminal via
sudo dpkg -i Downloads/libgl1-mesa-glx_22.0.1-1ubuntu2_amd64.deb or via a graphical package manager of your choice.
sudo apt install matlab-psychtoolbox-3 again. Now it should work.
If you appreciate this advice, a purchase of a Psychtoolbox paid support membership would be appreciated → help PsychPaidSupportAndServices.
-mario
Thanks so much! It worked! I tried to go to https://www.psychtoolbox.net, but Firefox gave me a security advisory, saying it was using a self-signed certificate. I decided against taking the risk for now, but will definitely budget for it next I land a grant.
Good. NeuroDebian also just reported back that the problem is now supposed to be fixed, so this workaround should not be needed anymore. But leaving it in place is not any problem either, the package just wastes a few kilobytes of disc space, so all should be fine.
Wrt. the psychtoolbox.net website, thanks for reporting this! This is some new issue, just two days ago there wasn’t any problem with the websites security certificate. Hopefully this will be fixed soon, by whoever screwed it up at our webhoster. There’s just no damn day ever without something going wrong 
-mario
Ok, psychtoolbox.net should work properly again, without any scary warnings from your webbrowser. Apparently some server certificate did expire and the webhoster didn’t handle this in time.
If you want to buy a support membership to support us, I can only encourage you. We need every cent for survival.