We keep getting the error "Preferred user information is currently unavailable" when trying to register a new user.

I have just expierenced same problem on my own dnn portal.

it's freshly installed 4.7 version with "typical" setup, everything seems to run smoothly but not users registration.

we already have ~ 17 users signed up, however today my friend could not register - he got same error like in the first post. I also checked and got same error. After next 5 minutes I tried again with same credentials - this time password validation worked out - I was asked to put 7+ symbols passw. (I used same passowrd both times, but only in second time it threw password validation error). So finnaly after I fixed the passw. my registration of new user passed the test.

however my other friend confirmed that he got same error yesterday, and only way to fix it is to use only small caps for desirable user name. (however my test of user registration succesfully was passed with one capitated letter).

I think this is DNN bug.

This error kept me up a long time.  It is frustrating because it makes little sense.  In addition to this error, I also got errors adding/deleting users in admin.  To fix it, I went to Admin > Site Settings and changed the registration to verified and then back to public.  Now, like magic, it works again.