DNS config error "sequence item 0: expected str instance, NoneType found"

I am using
root@ubuntu:/snap/maas/current# snap list
Name Version Rev Tracking Publisher Notes
core18 20220428 2409 latest/stable canonical✓ base
core20 20220329 1434 latest/stable canonical✓ base
lxd 4.0.9-8e2046b 22753 4.0/stable/… canonical✓ -
maas 3.1.0-10901-g.f1f8f1505 19835 3.1/stable canonical✓ -
maas-cli 0.6.5 13 latest/stable canonical✓ -
maas-test-db 12.4-22-g.aed1dfe 91 3.1/stable canonical✓ -
snapd 2.55.3 15534 latest/stable canonical✓ snapd

I am trying to edit a DNS entry on
http://10.156.20.248:5240/MAAS/r/domain/0

domain 0 is NOT the default domain any more (if that matters). When I save my changes, I get the error above. I also get that error when I try to delete it

sorry, @jeremy-mordkoff, i just saw this one. i obviously can’t follow the link you posted (it’s probably an internal address?), so i’m having a hard time visualizing how you’re getting to this error. that said, “NoneType found” is probably a Python error that shouldn’t be exposed.

so two choices, i think: show me in screenshots what you’re trying to do that’s causing the error, or just file a bug (which requires basically the same narrative).