I get 401 errors after updating to the latest version (or after manual install)

The 401 "forbidden" errors after upgrading on-premises helpdesk are due to the Windows XP/Vista/7/2008 NTFS "unsecure stream" feature. Files downloaded from the Internet remain "blocked" and show weird error messages until you unblock them. http://superuser.com/questions/38476/this-file-came-from-another-computer-how-can-i-unblock-all-the-files-in-a

The solution

Before extracting the files from the downloaded ZIP-archive, right-click the ZIP-file, select "properties", and click "unblock". Only after that - extract the files.
Solving problems with on-premises version of Jitbit Helpdesk ticketing system