I'm having the same problem it could be a problem with the mendix cloud???
I also got this problem
Medix mentioned this at 8:55 CET:
Failure to start app after new deployment
New incident: Investigating
We noticed apps can't be started after a new deployment. We are investigating the root cause of the incident.
Please hold any new deployments until this issue has been resolved.
We will update this incident as events warrant.
Check the most recent info via https://status.mendix.com/
Hello, I opened a ticket to support and they have changed the status page:
https://status.mendix.com/
It`s a problem with the cloud.
We only can wait to the fix.
Regards.
Mendix provided a hotfix for the issue. With this, the App starts.