Problem with Beta 5.0:
I have just updated my secondary pihole (piZeroW) to v5 beta for testing. It appears to be grossly working but I see this error on the web interface:
PHP error (2): fopen(/etc/pihole/adlists.list): failed to open stream: No such file or directory in /var/www/html/admin/scripts/pi-hole/php/savesettings.php:181
Your devug log shows that you missed to checkout the release/v5.0 web branch.
Please run
pihole checkout web release/v5.0
Everything should be fixed afterwards. Make sure you have cleared your browser's cache in case you still experience glitches after the checkout command.