I would like to address 2 things I have experienced on XBX. One is a solution to some of the posts I have seen. The other, I hope can pinpoint these crashing issues.
1.) If you are having difficulties downloading ANY mod (not just SSM2). First it would be a good idea to favorite any mod you have for easy location. Then try going into the manage game and add-ons section > saved data > reserved space > clear reserved space.
Then start the game back up and re-download your mods. This should remove the "operation could not be completed" message.
2.) I was playing SSM2 before the update and it was running perfectly. No crashes, no real bugs. However, after experiencing the above issue, I thought I was having crashes because of a save bug, by deleting and re-installing the mods. This does not seem to be the case. I have deleted ALL my saves (even the unmodded ones), and started over. The crashes do not start until you establish (from my experience) ANY settlement through the city planners desk. When loading into these settlements (if you can at all) there is a crash about 10 minutes after. Even if you load into a sim settlement and fast travel out, the crash will follow about the same amount of time.
However, loading a new save away from these settlements does not cause a crash, as long as you stay away from these settlements you can play regularly.
It seems reminiscent of a really bad memory leak, but I am not sure.