This time I started a moderate expansion to my base and managed a quicksave before it crashed. A message appeared when I reloaded:
Now, since you asked, so I have come to deliver.WARNING
This save is missing zone files.
This will likely cause issues such as missing player buildings
Please send us your save.log file to help us track down the problem.
Also, it's kind of exciting, as it's the first warning window I've enjoyed the pleasure of seeing since starting this save 170 hours of my life ago.
Note: I have 14 active mods
File: