You do not have an e-mail address.
Alert has been created successfully but you will not receive notifications until valid e-mail or mobile address has been provided in your profile
Got this error on your on-prem SP2013 while setting alerts?
The reason, in my case, was that User Property "Work email" wasn't setup correctly.
Don't worry , it is easy to get it straight and here is how:
1. Go to Manage User Properties, and find "Work Email", Edit
2. In the "Work Email" properties, add a new mapping "mail"
3. Make sure that Policy settings: Replicable, and Edit settings: Allow users to edit values for this property.