LG G3: "unknown error code when installing this app ' -505 ' "

[AC Question]

I have the LG G3 smartphone with the pre installed McAfee Mobile Security, which worked very well ... untill I wanted to upgrade my McAfee with installing the McAfee All Access Product on all of my devices (smartphone and laptops). The installation on my laptops did complete very well. But on my smartphone i got an error during installation:

"unknown error code when installing this app ' -505 ' "

so the installation could not complete and now when i want to open the McAfee Mobile Security app, it doesn't work at all because i get a white screen.

I did try anything to remove the preinstalled app. but nothing did work well.
How can help me out?

 

[B. Diddy]

Welcome to Android Central! Try going to Settings>Apps>All​, select McAfee, and tap Uninstall Updates. After the factory version is reinstalled, try updating it again in the Google Play Store.