Procedure
To check if the container running the Omnisharp-Theia plug-in is running OmniSharp, execute the ps aux | grep OmniSharp.exe command. If the process is running, the following is an example output:
/tmp/theia-unpacked/redhat-developer.che-omnisharp-plugin.0.0.1.zcpaqpczwb.omnisharp_theia_plugin.theia/server/bin/mono /tmp/theia-unpacked/redhat-developer.che-omnisharp-plugin.0.0.1.zcpaqpczwb.omnisharp_theia_plugin.theia/server/omnisharp/OmniSharp.exe
If the output is different, the language server has not started inside the container. Check the logs described in Checking important logs.