If custom Web UI TLS certificate is installed with a certain key size, GUI will be unavailable after upgrading to 9.0.0. Go to 9.0.1 or later instead.

Possible RPZ but that in some environments causes DNS process to core dump and restart until disk is full.

Do not run a GMC promotion if running Multi-Master DNS unless you have the hotfix installed. You will split the grid.

For NIOS Grid Upgrade, the Distribute and Test buttons in the main GUI might not work. Use the side buttons on the right instead.