https://connect.microsoft.com/IE/feedback/details/808279/ftpopenfile-and-internetwritefile-broken-changed-in-ie11 ( Clicked 337 times )
http://stackoverflow.com/questions/19683291/wininet-from-ie-11-randomly-returns-error-12003-for-most-ftp-functions ( Clicked 204 times )
It does NOT matter if you are using IE11 as your browser or not. It is only the fact that IE11 is even installed on your computer that causes this problem. The problem comes from the wininet.dll file being corrupted, not from the browser itself.
Microsoft has finally released a fix for this in the IE11 cumulative security update (MS14-010) released on February 11, 2014. Applying this should also resolve the error.
http://support.microsoft.com/kb/2909921 ( Clicked 340 times )
Other than uninstalling IE11, a few users have reported successfully working around this problem by doing the following:
- Select the Tools menu, then FTP Manager.
- In the Transfer Mode section, select the setting to Upload Files All At Once
In the few cases we have seen, making the above change, and/or installing the Microsoft Fix, has resolved the issue. If you have this issue please try the above and if you are still having problems after that please post a new thread on the message board for assistance.