Error: More than one user account has been created with the same email address

This is only possible if you have entered the email address the second time around with either leading or trailing spaces.

So the following are all treated as different email addresses:

username@abc.com

 username@abc.com(leading space)

username@abc.com (trailing space)

Make sure you therefore check that the email address is entered correctly without leading or trailing spaces if you want a user’s existing account to be updated. This is especially critical if you are using eCommerce commands to update existing user accounts.