Fix Windows Defender Real-Time Protection Turning Off Automatically - Fix Ubuntu APT Update GPG Error: No Public Key-Windows 10 Update 502 Error Troubleshooting

Updated 2026-06-13 14:52:55security-tools
Fix Windows Defender Real-Time Protection Turning Off Automatically - Fix Ubuntu APT Update GPG Error: No Public Key-Windows 10 Update 502 Error Troubleshooting
Before changing system settings, save your work and note the exact error text so you can compare results after each step.

Extra verification checklist

  • Restart the affected app after changing permissions or configuration files.
  • Test the same workflow in a clean browser profile or a temporary user account.
  • Compare the result on another network if the error may be connection related.