When Nexus is executed via a command line, an error is given:

The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detail.

Check the Nexus configuration file, Sdl.Nexus.exe.config for xml formatting errors.  Fixing this will resolve the issue.

Please note - If this change has been made following installation, or perhaps cloning of another TMS server, then Nexus should be fully reinstalled.  Additionally, the Nexus TMS user's password needs to be re-encrypted and that password added to the necessary Nexus configurations.