Applies to Product - Power Automate
What’s happening?
System.MissingMethodException when attempting to use the type CustomObject as an output parameter in a CustomAction within Power Automate Desktop. The error message indicates that the method cannot be found during the execution of the action.
Reason:
This is related to unsupported versions of the .NET Framework being used on the customer's machine. Specifically, versions 2.48 and 2.49 of Power Automate Desktop have known issues where custom modules created with actions containing custom objects as input or output parameters fail at runtime.
Resolution:
Update .NET Framework to at least version 4.7.2 or 4.8. This can be done by downloading the offline installer from the following links: