Issue:

 Installation of Silverlight fails with a generic error 1603 "installation failed" after the installation progress shows 99% complete.

Cause:

To find the root cause open the SilverlightMSI.log from the %temp% folder and it shows an error “Cannot create HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins\@Microsoft.com/NpCtrl,version=1.0”.

This is because a MacAfee ‘Access Protection rule’ has been set on ‘Mozilla & FireFox files and settings’ which blocks Silverlight installer from creating the registry key. When we open the Access Protection log from the MacAfee console we can see entries like below

“Blocked by Access Protection rule %username% C:\WINDOWS\regedit.exe\REGISTRY\MACHINE\SOFTWARE\MozillaPlugins\\@Microsoft.com/NpCtrl,version=1.0 Common Standard Protection: Protect Mozilla & FireFox files and settings Action blocked : Create”

Resoltuion:

 It is recommended to conatct MacAfee and Modify the ‘Access Protection rule’ on  ‘Mozilla & FireFox files and settings’, such that it allows Silverlight Installer to create the key. As a workaround we can disable ‘Access Protection’ from the MacAfee console, install Silverlight successfully and then enable ‘Access Protection’ back.

 Content by : Sarat Chandra