XF 1.5 New registration giving The field 'bacc1ac6a0fd239c10f751b143ebb88b' was not recognised.

[Doom PhD]

People trying to register new accounts on my board are getting the above error and being prevented from completing registration. Is there anything I can do to fix it?

 

[Paul B]

Disable all add-ons and revert to a completely default style.
Does it work then?