It looks like a very recent cups update has tightened acceptable contents of /etc/cups/cupsd.conf.

In my case, the offensive lines are:

JobPrivateAccess  default
JopPrivateValues  default
SubscriptionPrivateAccess  default
SubscriptionPrivateValues  default

These appear at the end of the file. Other copies of similar lines appear within sections of the file, such as < Policy authentication>.

Only the orphan lines at the end were offensive to

cupsd -t

Once converted to comments, printing is now working

It looks like a very recent cups update has tightened acceptable contents of /etc/cups/cupsd.conf.

In my case, the offensive lines are:

JobPrivateAccess  default
JopPrivateValues  default
SubscriptionPrivateAccess  default
SubscriptionPrivateValues  default

These appear at the end of the file. Other copies of similar lines appear within sections of the file, such as <Policy authentication>.

Only the orphan lines at the end were offensive to

cupsd -t

Once converted to comments, printing is now working