I have been trying to solve this for some time, and I have come to the conclusion that it is because content that is referenced in workflow instances has been deleted, then cleared from the trash can.
I get a PageNotFoundException - "Content with id 96396_120142 was not found", then it 404's.
This doesn't seem like a good way for the My Tasks AJAX request to fail, since one deleted page awaiting approval can destroy the content editor's entire ability to view their tasks, so it appears as if this is perhaps a bug to look at?
As a workaround, I would like to create a scheduled job that goes through all tasks with a given definition name (Parallel Approval), testing to see if the page is still valid, and deleting the task if it isn't.
Is there any way I can go through the tasks like this?
We have a Parallel Approval workflow set up on our site, so the admin needs to be able to see the "My Tasks" section of the "Tasks" tab in edit mode. All of the sections except My Tasks (Draft, Rejected, Ready to Publish, etc.) are working correctly.
I have used Fiddler to inspect what comes back from the AJAX requests the CMS is making to get these sections of the Task tab. The "My Tasks" section does an AJAX request to the following path -
The result is a 302 redirect to the 404 page.
As I said before, all of the other sections work OK, despite the fact that they are going to the same URL but with different data in the query string, e.g.
All of those work as expected.
I also want to add that this problem is only occuring on one of our environments. It works fine on other environments running the same code. There is a reasonably large list of running parallel approval workflow instances so there could be some data in there causing a problem, but clearing them out is not an option because there is a lot of content creation there.