In this guide:
- Am I affected? 3 quick checks
- Why the toggle is greyed out
- Fix 1: Microsoft’s official registry workaround
- Fix 2: the Group Policy route (Pro / Enterprise)
- Fix 3: the workaround didn’t restore the toggle — now what?
- Fix 4: verify it worked and watch for the real patch
- Do you actually need Smart App Control on right now?
- Frequently asked questions
If Smart App Control looks frozen in your Windows Security app — the switch is greyed out and nothing you click brings it back — you didn’t break anything. Microsoft’s October 2026 Patch Tuesday update did.
On October 13, 2026, Microsoft shipped KB5127648, the monthly security update for Windows 11 versions 24H2, 25H2 and 26H2. Microsoft confirmed a known issue: on some devices where Smart App Control had been turned off, the toggle can no longer be switched back on. Microsoft’s advisory puts it plainly — after installing this update, “the option to turn on Smart App Control might be grayed out.”
There is no permanent patch yet, but Microsoft published two official workarounds. This guide walks you through both, plus how to tell whether your PC is even affected and what to do if the workaround doesn’t restore the toggle.
Update: October 28, 2026. Microsoft's KB5127648 article still lists the greyed-out Smart App Control toggle as a known issue, and still says Microsoft is working on a resolution to arrive in an upcoming release. No permanent fix has shipped. The registry workaround and the Group Policy workaround documented in this post are unchanged and still match Microsoft's article.
Am I affected? 3 quick checks
Microsoft limits the bug to a specific combination. Run through these before touching anything:
- Windows 11 version. Open Settings → System → About and check the version. You need 24H2, 25H2 or 26H2. Smart App Control is a Windows 11 feature, so Windows 10 PCs are not affected at all.
- KB5127648 is installed. Go to Settings → Windows Update → Update history. The October update raises builds to 24H2 → 26100.9711, 25H2 → 26200.9711 and 26H2 → 26300.9711 — run
winverto confirm your build. - Smart App Control was Off — and the toggle is now greyed out. Open Windows Security → App & browser control → Smart App Control settings. If the switch is greyed out and it was Off before the update, you match Microsoft’s reported symptom.
Two important notes here. First, Microsoft says only some devices are affected — having the update installed doesn’t guarantee the bug. Second, if your PC never qualified for Smart App Control (it only activates on fresh Windows 11 installs; a PC upgraded from Windows 10 needs a reset or reinstall before SAC can ever be switched on), the toggle may have been unavailable long before this bug — and that’s a separate matter.
Same KB, different bug: KB5127648 is also the update that caused the Windows 11 mouse-stutter issue this week — Patch Tuesday has been rough for this one.
Why the toggle is greyed out
Smart App Control is the Windows 11 feature that blocks unsigned, untrusted and potentially unwanted apps using Microsoft’s app-intelligence services, working alongside Microsoft Defender and SmartScreen. Microsoft’s known-issue entry for KB5127648 says the update breaks the Off → On path: if SAC was already on, your device is unaffected and remains protected. If it was off, the setting can get stuck greyed out.
Microsoft is working on a resolution “in an upcoming release” — no date promised. Until then, the documented workarounds below are the official path back.
Fix 1: Microsoft’s official registry workaround
This is the workaround Microsoft documents for regular (non-managed) PCs. It flips two feature-override values and requires a restart.
- Back up the registry first. This is Microsoft’s own precaution: open Registry Editor, click File → Export, and save a backup of the full registry before changing anything.
- Open an elevated Command Prompt. Type
cmdin the Search box, right-click Command Prompt and choose Run as administrator. - Run these two commands exactly (copy them from here — don’t retype from memory):
reg add "HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides" /v 2883193997 /t REG_DWORD /d 1 /f reg add "HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides" /v 2850574478 /t REG_DWORD /d 1 /f- Restart your PC to apply the change, then reopen Windows Security → App & browser control → Smart App Control settings and check the toggle.
Note this is not the old VerifiedAndReputablePolicyState registry fix that May 2026-era guides (written for earlier greyed-out causes) recommend — that addresses a different problem. For the KB5127648 bug, only the FeatureManagement\Overrides key above is Microsoft’s documented workaround.
Fix 2: the Group Policy route (Pro / Enterprise)
For IT administrators on managed PCs, Microsoft offers a policy-based alternative. Download the two Group Policy packages from the KB page:
- Windows 11, versions 24H2, 25H2, and 26H2 - KB5074105 261015_19222 Feature Preview (enables Smart App Control)
- Windows 11, versions 24H2, 25H2, and 26H2 - KB5074105 261015_19221 Feature Preview (enables troubleshooting logging)
Install both, then set them to Enabled under Computer Configuration → Administrative Templates → {Group Policy name} → Windows 11, version 24H2, 25H2. Restart the affected device(s) to apply. Verify the exact path in the current KB before deploying — don’t guess a different template path for 26H2.
Fix 3: the workaround didn’t restore the toggle — now what?
If the registry commands ran and the toggle is still dead, check these before assuming the bug is unbeatable:
- Did you run Command Prompt as administrator? The commands must be elevated — a normal prompt will appear to succeed silently on some systems but change nothing. Right-click → Run as administrator, and re-run both commands.
- Is the PC domain-managed? Work or school PCs may be governed by organisation policies that override the local registry. Ask your IT admin — they’ll likely use the Group Policy route in Fix 2.
- Did your PC ever qualify for Smart App Control? Remember: SAC only switches on for fresh Windows 11 installs. If your machine was upgraded from Windows 10 and never reset, the toggle may have been locked before KB5127648 — and only a reset/reinstall changes that (Microsoft’s documented SAC requirement, not this bug).
- Did you restart? Both workarounds explicitly require a full restart — a shutdown with Fast Startup enabled sometimes isn’t enough. Restart from the Start menu’s power button.
Fix 4: verify it worked and watch for the real patch
- Reopen Windows Security → App & browser control → Smart App Control settings — the toggle should now respond.
- Run
winverand confirm your build matches the October line (26100.9711 / 26200.9711 / 26300.9711 for 24H2 / 25H2 / 26H2). - Keep an eye on the KB5127648 release notes for Microsoft’s permanent resolution. Once it ships in a cumulative update, undo any test tweaks you made outside Microsoft’s documented steps.
One more October-2026 note: this is also the last monthly security update for Windows 11 24H2 Home and Pro — Microsoft recommends moving to the latest Windows 11 version, as covered in our 24H2 end-of-support upgrade guide.
Do you actually need Smart App Control on right now?
Honest answer: maybe not. Smart App Control has three modes — On, Off, and Evaluation (Evaluation doesn’t block anything; it just observes whether your PC is a good candidate). Microsoft Defender keeps running regardless of the SAC toggle — the greyed-out switch doesn’t leave you unprotected.
So if you don’t need to enable SAC urgently, the safest play is to do nothing and monitor Microsoft’s KB for the permanent fix. Only take the registry route if you actually need the toggle back today — and back up the registry first, as Microsoft instructs.
Frequently asked questions
Why is Smart App Control greyed out after the October 2026 update?
Microsoft confirmed that KB5127648 (October 13, 2026) breaks the Smart App Control toggle on some Windows 11 24H2/25H2/26H2 devices where the feature had been turned off. The switch shows greyed out in Windows Security → App & browser control and can’t be switched back on. A permanent fix is coming in an upcoming release.
Can I turn Smart App Control back on without reinstalling Windows?
Yes — for this specific bug, no reinstall is needed. Microsoft’s documented workaround is two reg add commands (values 2883193997 and 2850574478 under HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides) from an elevated Command Prompt, followed by a restart. That said, SAC’s normal requirement still applies: if your PC was upgraded from Windows 10 and never reset, enabling SAC has always required a reset/reinstall.
Is editing the registry safe for this fix?
It’s safe when you follow Microsoft’s documented steps — but only then. Back up the registry (Registry Editor → File → Export) before running the commands, copy the commands exactly, and use an elevated Command Prompt. Don’t substitute registry edits from forum posts that you haven’t verified.
Does Smart App Control slow down my PC?
On supported hardware the overhead is minimal — it checks apps against Microsoft’s intelligence services at launch rather than scanning continuously. It won’t noticeably slow down gaming or everyday work. The bigger consideration is compatibility: unsigned or niche software can get blocked, which is why some users turn it off.
When will Microsoft release the permanent fix?
Microsoft says a resolution is coming “in an upcoming release” but hasn’t named a date or a specific cumulative update. Watch the KB5127648 release-notes page — once the fix ships, your toggle should behave normally after installing that update.