Windows 11 KB5077181 Boot Loop Fix: Emergency Recovery for February 2026 Update

What is the KB5077181 Boot Loop?

The Windows 11 cumulative update KB5077181, released on February 10, 2026, is causing critical boot loops on systems running Windows 11 24H2 and 25H2 (builds 26100.7840 and 26200.7840). Affected PCs restart repeatedly — some users report over 15 reboots — before landing on a broken login screen with a System Event Notification Service (SENS) error reading "The specified procedure could not be found."

Microsoft has not officially acknowledged this issue as of February 15, 2026. The boot loop is not listed in the update's known issues. The fix is to uninstall KB5077181 and pause Windows Update to prevent automatic reinstallation.

When does it occur?

• Immediately after KB5077181 finishes installing and the PC reboots
• During the login screen with a SENS service error blocking sign-in
• After multiple automatic restart cycles (15+ reported in severe cases)
• When the update installation fails mid-process with error code 0x800f0983 or 0x800f0991
• On systems running Windows 11 24H2 (build 26100) or 25H2 (build 26200)
• More frequently on systems with third-party antivirus or endpoint security software

Common causes

• KB5077181 corrupts the SENS service binary — the update replaces or modifies an exported procedure that SENS depends on, breaking the login chain
• DHCP Client service dependency failure — SENS and DHCP share early-boot service dependencies; when one fails, both can cascade
• Incomplete update installation — power loss or forced shutdown during the update process leaves the system in an inconsistent state
• Conflict with third-party security software — endpoint protection tools hooking into early boot services can interfere with the update
• Insufficient disk space — the update requires free space on the system partition for rollback data
• Existing Windows Update corruption — previous failed updates (especially KB5074109 issues) compound with KB5077181

Step-by-step fixes

1. If your PC can still boot — uninstall via Settings — Go to Settings > Windows Update > Update History > scroll down > Uninstall updates. Find "Security Update for Microsoft Windows (KB5077181)" and click Uninstall. Restart when prompted. Then immediately go to Settings > Windows Update > Pause updates and pause for at least 5 weeks.

1. If your PC cannot boot — enter Windows Recovery Environment — Force-interrupt boot 3 times in a row: power on, wait for the Windows logo, hold the power button for 10 seconds to force shutdown. Repeat 3 times. On the 4th boot, Windows will launch the Recovery Environment automatically.

1. Uninstall from Recovery Environment — In WinRE, go to Troubleshoot > Advanced Options > Uninstall Updates > Uninstall latest quality update. This removes KB5077181 without needing to log in. Restart and verify the system boots normally.

1. Alternative: use Command Prompt in WinRE — If the GUI uninstall fails, from Troubleshoot > Advanced Options > Command Prompt, run: wusa /uninstall /kb:5077181 /quiet /norestart then type exit and restart. If wusa is unavailable, try: dism /image:C:\ /remove-package /packagename:Package_for_RollupFix~31bf3856ad364e35~amd64~~26200.7840.1.1

1. Pause Windows Update to prevent reinstallation — After uninstalling, immediately go to Settings > Windows Update > Pause updates. Select the maximum pause duration. Without this step, Windows will automatically download and reinstall KB5077181 within hours, restarting the boot loop.

1. Fix SENS error on login screen — If you can reach the login screen but see the SENS error, press Ctrl+Alt+Delete, then click the power icon > Restart while holding Shift. This enters WinRE directly. Follow steps 3-4 above.

1. Run System File Checker after uninstall — Open Command Prompt as Administrator and run: sfc /scannow followed by DISM /Online /Cleanup-Image /RestoreHealth. This repairs any system files corrupted during the failed update.

1. Check your build number — Press Win+R > winver. If your build is 26200.7840 or 26100.7840, you have the problematic update installed. After uninstalling, the build number should revert to the previous cumulative update level.

If it still doesn't work

If WinRE cannot remove the update, boot from a Windows 11 installation USB drive (downloadable from microsoft.com/software-download/windows11) and use the repair options from there. In extreme cases, use the Command Prompt from the USB to manually rename the problematic update files in C:\Windows\WinSxS\. Monitor the Windows Release Health dashboard at learn.microsoft.com/windows/release-health for Microsoft's official acknowledgment and a corrective patch. Do not manually install any replacement updates until Microsoft confirms a fix — the issue may recur with the next cumulative update if the underlying SENS dependency is not resolved.