Typically, this is a result of the password being expired or a password change being required.
Try to log in through [yourBBNCdomain]/login.aspx. If your password is expired or a password change required, you'll be prompted to reset a new password.

If this is occurring for a user, who is not a Supervisor user, this indicates the user may have been created through the Add Users Utility or through Users & security > Users. When a user is created through the Add Users utility within the NetCommunity plugin inEducation Edge or through the Users gallery in Blackbaud NetCommunity, they will be prompted to reset their password the first time they log in.
There are a few ways the user can reset their password: We are currently evaluating this issue and will update this article when we have more information.

In the interim, you may consider updating the Form Display part to include text indicating one of the options listed above. To edit the form display part text:
  1. Edit the Form Display part associated with the form the user is trying to access
  2. Select the Helplets tab
  3. Select Login from the dropdown
  4. Enter your desired text
  5. Click Save

See also: Error: Password change required. Click here to go to the admin login page. - when logging in