There was a problem updating the submission - error message

[caldwelr]

I am unable to enter grades in Grades and in SpeedGrader.

[kellecr1]

I know this isn't solving the problem exactly but the solution I came up with was to duplicate the assignments, reenter the grades and then delete the old assignment. 

[CelestialDawnA]

I know this is quite late to answer this question after when this originally was asked, but we had similar issues and found a quick resolution in case anyone else happens to see this error pop up again and finds this thread. We had been looking everywhere for a similar case and pretty much only found this one for the error, but we came up with our own solution anyways. In case anyone is in the same boat, here is what we did to resolve that error.

Specific issue:

Midterm exam had several students who did not submit the quiz, but the instructor could not input "0" grades for those students to make sure their course total scores reflected that missing grade. Instructor received the same error as listed in this question ("There was a problem updating the submission"). This was the only assessment where that happened, so it is currently unknown how it developed that problem.

Investigation:

We discovered that when we were getting that error it affected only those specific students and also seemed to exclude them from the SpeedGrader completely (ie, they were not listed as potential students to review/score), even though 1) the "Assign To" setting on the quiz was set to "Everyone" in the course being assigned to it and 2) the students were showing up in the normal grade center view as active students. With the discovery that they were excluded from the SpeedGrader, we believed that to be the root of why the traditional gradebook view was not allowing the input of manual scores. With that in mind, we tried to find a way to force Canvas to show the student(s) in the SpeedGrader and see if that fixed the problem.

Solution:

To fix it, we changed the "Assign To" area to just list one of the affected students, saved that change, and then verified that they now showed up in the SpeedGrader for that assignment. With that verified and also confirming that we could put in a "0" score for that student, we went back to the quiz and changed it back to be assigned to everyone in the course. With that change, all affected students could now be given the 0s for their missing attempt.

TL;DR: Change the "Assign To" settings to list one particular student, save the change, then go back and edit the "Assign To" to be set to "Everyone" again. Saving that should reset the issue and bring back the ability to modify their scores.

Conclusion:

Again, we don't know what prompted the error in the first place, but that solution seemed to fix it very quickly while also preserving the attempt data for all students in the course. No need for extra assignments / grade columns!

Hope this helps any others who happen to run into this issue.