How To Get User Data in Callback Function for pre_user_nicename?

If anyone should be faced with this problem, check if you have defined a callback function to set the user_login on pre_user_login. This filter is applied inside the wp_insert_user()-function and produced a same username again. Therefore the nicename was changed by adding a “-2”.

So, my problem was that I reset the user_logins again and again, instead of only once when registering.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)