MyBB Community Forums

Hi!
Im confused to this error.
I created a forum for a friend a few days ago, I didnt do anything to the database, or even edit something in the ACP.
Its giving me this error.

MyBB SQL Error
MyBB has experienced an internal SQL error and cannot continue.

SQL Error:
1062 - Duplicate entry '' for key 'loginname'
Query:
INSERT INTO mybb_users (`username`,`password`,`salt`,`loginkey`,`email`,`postnum`,`threadnum`,`avatar`,`avatartype`,`usergroup`,`additionalgroups`,`displaygroup`,`usertitle`,`regdate`,`lastactive`,`lastvisit`,`website`,`icq`,`aim`,`yahoo`,`skype`,`google`,`birthday`,`signature`,`allownotices`,`hideemail`,`subscriptionmethod`,`receivepms`,`receivefrombuddy`,`pmnotice`,`pmnotify`,`showimages`,`showvideos`,`showsigs`,`showavatars`,`showquickreply`,`showredirect`,`tpp`,`ppp`,`invisible`,`style`,`timezone`,`dstcorrection`,`threadmode`,`daysprune`,`dateformat`,`timeformat`,`regip`,`language`,`showcodebuttons`,`sourceeditor`,`buddyrequestspm`,`buddyrequestsauto`,`away`,`awaydate`,`returndate`,`awayreason`,`notepad`,`referrer`,`referrals`,`buddylist`,`ignorelist`,`pmfolders`,`warningpoints`,`moderateposts`,`moderationtime`,`suspendposting`,`suspensiontime`,`coppauser`,`classicpostbit`,`usernotes`) VALUES ('Jake12','8e6ceaeb24189979b97b124afb7a976f','G57QcNV4','D9tRa5tYJh52FLiLDIubhMExNukyJ79oP4KKfG2xr4nakpCRKR','[email protected]',0,0,'','',2,'',0,'',1483219787,1483219787,1483219787,'',0,'','','','','','',1,0,0,1,0,1,0,1,1,1,1,1,1,0,0,0,0,'1',2,'linear',0,'','',X'5b411937','',1,0,1,0,0,0,0,'','',0,0,'','','',0,0,0,0,0,0,0,'')
Please contact the MyBB Group for technical support.

It happens, when i try to register.
(The error as an image)

Would appreciate some help,
With best regards!
Jake

This seems to be caused by a plugin as loginname isn't a default column.