This can happen as a result of a duplicate record with that email address or after a record merge has occurred and the source record was deleted. Perform each of the below steps until the issue is resolved:

Step #1: Confirm if there is another patron with this same email address on file:
  1. Navigate to Analysis, then click on Information library
  2. Click to Add an ad-hoc query
  3. Select the source view of Constituents and click OK
  4. In the left column, select Online Information. From the middle column, drag Username into Include records where. Set this Equal to the Email address you are trying to add.
  5. Click Preview Results
  6. If there are any records appear in your results, you will need to edit the email address on that record's Online info tab, or merge the two constituents if these are duplicate records.
Step #2: If no records show in your results from above step, have the patron create their new account:
  1. At top right of your web forms, have patron click Register
  2. Enter new email and password to create account