Failed to install Sophos Anti-Virus for Windows: 8000ffff

Question

I have a remote user trying to install Sophos on their laptop. It's errored out every time. The error message is "Failed to install Sophos Anti-Virus for Windows: 8000ffff" . I've un-installed, rebooted, re-installed. Same error. Not sure what to do next.

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Mitch_51 · Answer

Good Evening, I've experienced a similar issue where Sophos Central reported the following error below: &bull; Failed to install Sophos Anti-Virus for Windows: 8000ffff 
 From the users perspective they saw a "Installation Failed" message. Upon some investigation, I narrowed it down to a conflicting AV, i.e. McAfee. I'd recommend seeing whether this the problem you're experiencing. 
 
 Remove the pre-existing AV (McAfee), 
 Remove Sophos Endpoint Protection, 
 Restart PC, 
 Then reinstall using the "SophosSetup.exe".