The deeplink module is used with an attibutre in an entity (portaluser.confirmationid). Deeplink module finds the portaluser automatically, great. But.... if this id is already handled an error message is shown. The requested object does not exist or you (Guest_7a658825-aafe-4929-836c-c84b4a39be3a) do not have the permissions to view the object. You can try to either navigate directly to the application or login again. Can I replace that with a custom error?
Chris de Gelder
The only way to display custom errors is to pass the argument as string instead of as object. Then you can retrieve the object yourself in a microflow, and do display anything you want. However the whole application will be loaded first, so its a bit slower.
(Or you just modify the java code in the module ;-))