Microsoft Remote Assistance didn't report any errors, but it didn't create the invitation file
When a helpdesk operator wants to start a Remote Assistance session with a user, a request is sent to the user session behind the scenes, so a Remote Assistance invitation is generated and sent back to the operator.
In the machine where the user session is hosted, the Microsoft Remote Assistance executable is executed to generate the invitation file and send it back to the helpdesk operator.
This message indicates that, although Microsoft Remote Assistance didn’t record any error in the Windows Event Log of the user’s session during the generation of the invitation file, the file itself could not be found. It could be due to many reasons, including the user not having write permissions in the temporary folder to save the file. The “Start Remote Assistance” job will contain further details about the errors.