Issue I face is when the same user has pending task which is created from revocation of identity certification, this api gives 500 internal error, it doesn’t give the response of any other manual tasks pending on this user.
Since you are getting a 500 internal server error, this tells me that there is likely a bug on the backend. This will have to go through our support channel so that engineering can better engage with you. They will likely need logs and more details about your environment to isolate the issue.
Please open a support ticket at https://support.sailpoint.com. If you get this solved, I would love to see what the solution is back in this thread