Today I ran into the following error, after I found the following request on the Flow community site.
BadRequest. The request failed. Error code: 'InvalidApprovalSubscribeRequestAssignedToMissing'. Error Message: 'Required field 'assignedTo' is missing, empty, or contained no valid users.'.
It just sounds like I’ve typed the user account incorrectly in my Start an Approval action but I have not.
Then I replaced the account with a different Office 365 account and all worked fine.
Hmm, what is missing? My Trial environment definitely had a user account created for meganb!
Or did it? I checked all my users and there is no meganb. Hmm, not sure why these demo environment give me these accounts that don’t really exist.
Then I thought about external users.
And As expected I got the same error again
My conclusion is to avoid this error you will have needed to add the user ( internal or external) to your environment either as a user or as an external user.