When upgrading a site to 6.0-beta3 a warning message appeared on the screen which started out something like:
"Saving an old version of the welcome..."
I only got to read the first few words of the message before it disappeared from the screen as other update progress information appeared. The message wasn't available after the upgrade completed and I couldn't find them logged anywhere (watchdog/DBLog). These messages should be left on screen or made available somehow for viewing after the upgrade is complete.
Issue arose using firefox 188.8.131.52.