ZDoom

What you are doing is unsupported and discouraged.

I am not going to say you can't do it - because you are free to do so - but we are not going to accept bug reports for an old release, we are not going to help you get an old release working if it breaks, and the old release has two major security flaws that have recently been patched.

You are completely on your own.

Hello, I solved the problem by removing GZDoom and from https://zdoom.org/files/gzdoom/bin/ I downloaded the 3.1.0 release and installed it. To prevent GZDoom to be updated, I removed the http://debian.drdteam.org/ package repository.

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-4.9 g++-4.9
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9

sudo apt-get install gcc-4.8 g++-4.8
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.8

sudo update-alternatives --config gcc

NOTE: I thought I had originally posted this as a logged in user, but realised I'd forgotten to log in. Sorry for the duplicate post, I'd delete it if I could...

After reading too many StackOverflow answers, I came across the possible issue, and a solution that worked for me. GOMP 4.0 was included with GCC 4.9; it seems our version of Ubuntu/Mint uses GCC 4.8, which uses a previous version of GOMP, which is causing the error. So, we need to install GCC 4.9, and make sure the OS uses it.

This link has the steps I used to do that.
https://askubuntu.com/questions/466651/how-do-i-use-the-latest-gcc-on-ubuntu

Super short version, open a terminal, and:
[code]
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-4.9 g++-4.9
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9
[/code]

Just in case you need 4.8 for anything:
[code]
sudo apt-get install gcc-4.8 g++-4.8
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.8
[/code]

And use:
[code]
sudo update-alternatives --config gcc
[/code]
to check version and switch between them.

Of course, this is an "at your own risk" situation, but I hope it helps :)

All I can suggest is contacting Blzut3 about this. He's the official package maintainer and also the one who actually signs those packages, making them official (at least inasfar as Ubuntu allows them to be official when using a custom repo).

My bad, after reading error message once again I understood that the OpenML library is installed but it's version is too old.
Unfortunately I have no VM image with Linux version affected by this issue. So I cannot provide a verified workaround at the moment.

I've been having the same issue as well. I already have libgomp1 installed, yet it won't start up.

We have OpenMP as optional dependency. Apparently Blzut3 wasn’t aware of this.
Installing [b]libgomp1[/b] via package manager should fix the problem.

You might want to register an account and send a PM to Blzut3 for this, since he is the one who manages the debian packages.

I'm getting this error at GZDoom 3.2.1 startup on Linux Mint 17.3:

/opt/gzdoom/gzdoom: /usr/lib/x86_64-linux-gnu/libgomp.so.1: version `GOMP_4.0' not found (required by /opt/gzdoom/gzdoom)

I guess there are some dependencies missing in the deb package and thus causing this problem on Ubuntu 14.04 based distros.
The libgomp version is 4.8.4-2ubuntu1~14.04.3