If this error occurs on a second attempt at uploading an attachment to a class or assignment, the file has already been written to the Downloadable documents Hosting folder but it will not show in FAWeb (or NetClassroom) because there was an issue/error during the upload process.

When FAWeb is hosted, the documents folder is structured with a folder for each class based on the class system record ID. The classes in the files folder are listed by system ID.  To match class with system ID, it’s possible to create a query and output the system ID or the import ID of the class (the system ID is the second half of the import ID) if working with multiple classes.  If the system ID is needed for just one class, it's possible to open the class and choose File > Properties from the menu bar. The file will be within the class folder. If the file is linked to an assignment, it will be within that assignment folder in the class folder.  Any partially uploaded files show with 0kbs.

1. Log into your Hosting files folder  with any Hosting credentials
2. Locate the Class folder > which will be located under /[siteID]/EE/Downloadable Documents
3. Locate the assignments folder if the file is linked to an assignment
4. Delete the 0 kb file

OR

1. Change the name of the file and try to upload the file again.