Hi,
Basically you cannot have a dot with your login name for security reasons. However I found a wordpress article that can allow this.
https://wordpress.org/support/topic/usernames-with-dots-not-working?replies=6
modifying the function wpmu_validate_user_signup in /wp-includes/ms-functions.php in line 524 from
preg_match( '/[a-z0-9]+/', $user_name, $maybe );
to
preg_match( '/[a-z0-9.]+/', $user_name, $maybe );
Thread Starter
Ati74
(@ati74)
I found this discussion too, but i don´t want modify any core-files.
I hoped there is an another solution.
You might want to try this by duplicating the ms-functions.php file, change the code in the duplicate file and rename the original to ‘ms-functions.php_’. Check if it will work and if not then you can delete the duplicate and restore the original file.