Bitdefender anti-virus (most likely the best and fastest protection software around) had a false-positive for malware on this website and MOSS.
This false-positive resulted in the website not being accessible and the ‘Can’t update error 3!’ error.
Both have been investigated by Bitdefender and are now fixed. It took them 3 days from the time I sent my mail. If you have the error 3 code and use another program besides bitdefender, please contact the support of your corresponding program and ask them to remove the falve-positive on moss.exe or make them check to get it working again 🙂