Foundation app is blocking apps trying to install how can i fix it?

[AC Question]

I'm trying to install some apps and it gives me a message saying that the foundation app installed on my phone is blocking them from being able to be used. It's says to uninstall the foundation app then try again but the uninstall is unsuccessful!! I went to my app manager and did a force stop & disable bit it still gives me the same message!! It's so annoying please someone help me work past this issue!??

 

[MoboPlay]

Do you mean native system app by foundation app? System apps can not be uninstalled. You can only downgrade them to a previous version by tapping the Uninstall button.

On the other hand, you can refer to the answer below:

By default, your phone's security features will not install APK files from "unknown" sources.
Have you gone to your /settings/general/security/ options and turned off the security block?