Fix Windows Update 404 Not Found Error on Windows 10 - Windows Security Certificate Error in Outlook 365: Fixes-Windows Security Not Loading After Update? Try These Fixes
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.