UPDATE: tested it with the original MF.
This MF is started at login. Basec on some conditions and user roles it will show either a Homepage or a page to enter Company data.
In this login a call another MF (either (OPN_Homepage or OPN_Company).
MF OPN_Homepage starts with a CLOSEPAGE activity. At the end of the Login MF it crashes. Those errors are shown after the End event of the Login MF.
The MF OPN_Homepage is also started from the Navigation panel. Then it works without problems.
Removed the CLOSEPAGE activity.
Running the login MF again and now the page will show, no errors.
So it seems that the CLOSEPAGE activity is the culprit.
Does it have to close a page during the Login MF? Yes, to log in the user have to fill in username/password in a popup window. So there is definetely a page to close. (we use the ForgotPassword/Deeplink modules)