php - Why might a file only be partially uploaded?

Question

Why might a file only be partially uploaded?

I am improving error-handling in my PHP file upload script and am trying to figure out how to handle UPLOAD_ERR_PARTIAL properly.

Should I prompt the user to try uploading the file again, or should I inform them that there is a more severe problem which is preventing them from uploading a possibly legitimate file?

Answer 1

UPLOAD_ERR_PARTIAL is given when the mime boundary is not found after the file data. A possible cause for this is that the upload was cancelled by the user (pressed ESC, etc).

I think it's enough to inform the user that the file is only partially uploaded and a retry will fix the problem.