Hi Teik, 

Welcome to Box Community and glad to assist! 

Upon checking, your upload error occurred on your collaborated folder. Note that the folder’s ability to store more files varies according to its owner’s storage allocation.

At this rate, please reach out to the owner and have him/her check his/her current storage.

Thanks for posting!

Thanks for the feedback Rona. I am the owner of the file and it seems that my current storage is more than sufficient. That's why I am puzzled. Will try to reach out to the Company and see if they can assist me. Thank you.