Microsoft confirmed a new issue today that is affecting users of the Windows 10 operating system. The issue prevents the start of certain apps, if they are started by a non-admin user.

Windows 10 systems that have the latest preview update installed are affected, according to Microsoft.

Note: Optional updates for Windows should be considered Beta, which means that they should not be installed on most systems. The only exception to the rule is if an update fixes a major issue that is experienced on a system. All changes of optional updates are included in the cumulative updates of the following month.

Here are the details:

• This issue affects Windows 10 systems with KB5043131 installed.
• Affected apps include Quick Assist, Microsoft Teams, and Windows Narrator among others.
• Microsoft started a rollback to resolve the issue on most systems.

Some Apps won't launch anymore

The issue affects only apps that launch from "a secure path" and request higher privileges using the attribute uiAccess=true. This means that the issue occurs only when a user is signed-in with regular user privileges and not admin privileges.

Tip: it may be possible to bypass the issue by right-clicking on apps and selecting to run them as administrator. Administrators may still run into the issue, according to Microsoft's description.

Microsoft lists four examples for secure paths in Windows 10:

• %ProgramFiles% (including subdirectories)
• %ProgramFiles(x86)% (including subdirectories for 64-bit versions of Windows)
• %systemroot%\system32
• %systemroot%\syswow64 (for 64-bit versions of Windows)

Any app that launches from these directories and that makes the request is affected by the issue.

Administrators may monitor the issue using Procmon. Check if an app runs with the integrity level low instead of medium.

The fix

Microsoft mitigated the issue using a Known Issue Rollback. This removes code from the update that is causing a issue. The change is applied automatically to non-managed devices. Most consumer devices and any business device that is not managed by an IT department will receive the fix in the coming 24 hour period.

The fix is not applied on managed systems automatically. A policy is provided by Microsoft that needs to be set on affected systems to apply the change.