I had this happen with recent xorg update from Sid.
Log said that (proprietary) Nvidia driver was no longer compatable with the new Xorg version. So I ran its installer (version 260) with update which downloaded and installed version 270 (but did not keep that installer!) and this works fine.
Since 270 is the current version on Debian, how would I go from Nvidia's installer to Debian's version, preferrably using the DKMS?
The proprietary version works first time, every time, but still (after all this time) leaves the text mode of the terminal, i.e. from control/alt/F1, messed up.