I am using dropzone extension for Yii framework to upload some files by registered users. Everything working well but some users for some files that they trying to upload it
in my case, the "partially uploaded" problem happened when uploading medium/large files using a slow internet connection.
The solution that works for me was set some Apache configurations in httpd.conf file:
TimeOut 300
KeepAliveTimeout 10
RequestReadTimeout handshake=0 header=20-1200,MinRate=200 body=20,MinRate=200
I hope it help.
As php documentation says, this error is
UPLOAD_ERR_PARTIAL is given when the mime boundary is not found after the file data.
A possibly cause for this is that the upload was cancelled by the user (pressed ESC, etc).
Also there are some more variants to check:
Permissions are wrong (i doubt, cause it will break all users).
Not enough free space on server.
This error occures when uploading from iOS.
This error can occure when uploading folder (due to browser limitations). On Mac OSX it occures 100%.
So this is possible errors to check. Hope this will help.