Please note that orca 4 and newer versions are not supported on the Euler cluster and will stay in the new module category. They are provided on an as-is basis as the developers of orca provide only precompiled binaries without any suitable documentation, change logs or list of known issues. The HPC group and some cluster users tested orca 4.0.0 and the bugfix release 126.96.36.199 (orca developers don't provide any information what bugs are fixed with the new release) and noticed problems, when using more than 1 compute node (24 cores). Therefore if you would like to run orca 4 and newer versions on the Euler cluster, then we recommend to use only up to 24 cores.
We have tried to investigate these problems, but since the mpirun calls are hidden in the (stripped) binaries, we don't know how orca calls mpirun and we can not modify anything as we do not get access to the source code. Further more, the end user license agreement (EULA) explicitly forbids decompiling and/or reverse engineering the orca software.
If you encounter a problem with running orca, then please contact the orca developers.