Hi Priya, this error can happen due to
1. No internet connectivity (Poor internet connectivity is not a problem).
2. The underlying microflow being called has thrown an exception which has not been handled.
You can surf the logs for answers, provided they give you some plausible insights.
The actual solution would be for the developer to update the app and handle the exception scenario in the microflow.
Hi Priya,
If you get this error 'contact your system administrator' error in microflow under call REST add a log message activity select error and trace the error message. Please follow the below documentation for handling errors.
https://docs.mendix.com/refguide/error-handling-in-microflows/