UpdateAsync throws "User with old email does not exist in Auth0 database"

I am trying to update a user in a custom database to mark them has verified.

When I try to call the update I received this error message:

“User with old email does not exist in Auth0 database”

My code looks like this;

var request = new UserUpdateRequest()
            {
                EmailVerified = update.EmailVerified,
                Connection = _managementClient.Connection,
                
            };


            var user = await _managementClient.Client.Users.UpdateAsync(id, request, cancellationToken);

   

What is causing this error message? I am not changing the email address and the user still exists in the Auth0 admin portal.