Bug #1624644 is a very old one, marked as fixed, with considerable discussion and confusion.
This bug is a clear indication that as of 16.04LTS, a bug exists with /boot filling up. Maybe it's the same cause, maybe it's different cause. This bug is trivial to reproduce: it happens on freshly installed stock no-changes versions of 16.04 if LVM is chosen, and the machine is left idle for 3 or more update cycles.
Bug #1624644 is a very old one, marked as fixed, with considerable discussion and confusion.
This bug is a clear indication that as of 16.04LTS, a bug exists with /boot filling up. Maybe it's the same cause, maybe it's different cause. This bug is trivial to reproduce: it happens on freshly installed stock no-changes versions of 16.04 if LVM is chosen, and the machine is left idle for 3 or more update cycles.