Symptom:

Your DNN installation returns the following error:

A critical error has occurred.
The E-mail supplied is invalid.

This error occurs when either:

1. You have an e-mail address on one of your accounts on DNN that has a invalid character or format.
2. You have two e-mail addresses that are set as the same thing and have this enabled in your web.config:

    requiresUniqueEmail="True"

Solution:

There are two approaches:

1. change the parameter in your web.config from requiresUniqueEmail="True" to requiresUniqueEmail="False"
2. Modify the entries in your DNN database:
   • Go into your database*, open the table called dbo.aspnet_Membership
   • Edit the fields for Email and LoweredEmail (Which should be the same value) change this to make this "valid" or "unique" if you do not want to turn requiresUniqueEmail option to "False" in your WEB.CONFIG file.

*To modify an MSSQL database:

• For SHARED HOSTING and MANAGED SERVERS (DEDICATED or VIRTUAL):
  • Log into your Plesk Control Panel, click the domain, click DATABASES, click DB ADMIN icon which will launch the web-based DB Admin tool for your server/database.
• For DEDICATED or VIRTUAL SERVERS (not managed), install and use MSSQL Mgmt Studio on your server to connect to your MSSQL instance.