Hmm may need to see a snippet from the client log, or at least the ActionScript line that returns that error code.
In an action the ‘exit code of action’ is the errorlevel returned by the most recent ‘wait’ command, so if you have more than one command line you can only determine the return code of the most recent one.
And, yes, ‘126’ is that the command could not be executed, and it’s usually because of an incorrect PATH or fully-qualified path to the command line is not correct. Also if you are depending on some environment variables, those usually aren’t processed by the non-login, root shell that we launch (i.e. “.profile” or “.bashrc” or something may not have been sources by the shell)