Can no longer log into CUPS web admin on macOS Mojave Beta? I have a printer and I'm trying to set the default paper size. Normally, I can do this via the cups webadmin localhost:631 

If you make any changes to a printer, it asks for your login credentials via an http basic auth request. On previous versions of Mac OS/OS X, you would use your 'short name' login and password for that computer. My Macbook Air is running the latest Mojave release 10.14 beta and now that no longer works. It asks for the password, but rejects it. I am sure the short name/password i am using is correct, as that's the one you need for all the auth system changes. 

Has anyone else had this problem? Does anyone know how to log in to the CUPS webadmin to make changes to a printer's default settings?
I had to enable the cups webinterface first: 
Open a terminal and type: 

sudo cupsctl WebInterface=yes


Confirm with &lt;enter&gt; and enter your password. 

Then authentication as described worked fine (on the final Mojave, though, not the beta)