Windows v15 sp4 install - "disk1.cab has invalid digital signature"

[3CXusername]

Windows Server 2008 R2 x64. All Windows updates applied.

• Tried KB3004394 as well as enabling "Allow software to run or install even if the signature is invalid".
• Tried downloading multiple 3CX sp4 installers all same outcome.

Attempting upgrade from v14 sp3 to v15 sp4. Uninstalled v14 components and on v15 install getting this:



Any ideas?

thanks in advance

 

[Sopock]

Outdated OS certificates ?
http://www.advancedinstaller.com/user-guide/tools.html

 

[Alex Esterkin]

Chances are, you have turned OFF Automatic Root Certificate Update. For example, if you use DigiCert certificates , as I do, you may have turned it off on the Tools tab. Re-enable the Automatic Root Certificate Update policy, and you will be able to install 3CX server.