Well i no this topic is old and i just had this problem my self and the solution was quite easy for me i hope this will help others in the future i found out after 2 hours of moving worlds one by one to see if it was the world nope then i check the plugins one buy one nope it was not the plugins then others told me to use a chunk fixer no im not so i said to my self wait the err said nbt tag wait what goes with nbt ?... players do. So i went threw the folders and found one called players data i said to my self what if i delete the folder. So i made a back up and erase the folder and restarted my server and there it goes it come on with out any err's huh. So this has nothing to do with chucks but rather the player's data. Now mind use that when deleting the folder u can erase players items and progress good luck to all. [/p]