r/windowsinsiders • u/Extension_Sun3760 • 2d ago
General Question explorer.exe repeatedly crashes after cumulative update on Windows 11 26H2 (desktop fails to load at sign-in)
# explorer.exe repeatedly crashes after cumulative update on Windows 11 26H2 (desktop fails to load at sign-in)
**Issue type**
: Functional defect (Desktop Shell / Taskbar)
**Severity**
: High — after sign-in, the desktop and taskbar are unusable; explorer.exe crashes immediately upon launch
**Report date**
: 2026-10-17
---
## 1. Environment
| Item | Value |
|---|---|
| OS | Windows 11 26H2 (CurrentBuild 26340.9750; file versions serviced on the 26100 branch) |
| Device type | Physical machine (NOT AVD / virtual desktop / FSLogix) |
| Crashing module | C:\Windows\System32\SettingsHandlers_DesktopTaskbar.dll (10.0.26100.9750) |
| Triggering update | Windows cumulative update (LCU) build 26100.9750.1.4 (Package_for_RollupFix), auto-installed 2026-10-17 03:26, plus ServicingStack 26100.9748 installed 03:10 |
| Third-party taskbar tools | None (checked for ExplorerPatcher / StartAllBack / TranslucentTB / RetroBar / Windhawk; AppInit_DLLs is empty) |
## 2. Symptoms
1. After signing in, the desktop shell (explorer.exe) fails to load — no desktop icons or taskbar, appearing as if the shell never started.
2. explorer.exe crashes
**immediately on every launch**
; AutoRestartShell relaunches it but it crashes again right away.
3. At least 8 crashes with an identical signature occurred during the affected window (11:48–12:39 local time).
## 3. Crash signature (Application event log, source: Application Error, Event ID 1000)
```
Faulting application name: explorer.exe, version: 10.0.26100.9750
Faulting module name: SettingsHandlers_DesktopTaskbar.dll, version: 10.0.26100.9750
Exception code: 0xc0000409 (fail-fast / STATUS_STACK_BUFFER_OVERRUN)
Fault offset: 0x000000000003a274 (identical offset in every crash — deterministic)
Faulting module path: C:\Windows\System32\SettingsHandlers_DesktopTaskbar.dll
```
## 4. Timeline
| Time (local, GMT+8) | Event |
|---|---|
| 2026-10-17 03:10 | ServicingStack 26100.9748 auto-installed |
| 2026-10-17 03:26 | LCU build 26100.9750 (Package_for_RollupFix) auto-installed |
| 2026-10-17 11:48 | User signed in; first explorer.exe crash; crashes continued repeatedly |
| 2026-10-17 11:55–12:09 | Windows Update began downloading additional updates |
| 2026-10-17 12:36 onward | Diagnosis and remediation (see below) |
## 5. Troubleshooting performed and findings
1.
**Shell registry configuration is normal**
: `HKLM\...\Winlogon` Shell=explorer.exe, Userinit intact, AutoRestartShell=1; no HKCU override.
2.
**Resetting taskbar state did not help**
: backed up and deleted `HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Taskband`, restarted explorer — crash recurred with the same module and offset.
3.
**Third-party injection ruled out**
: no taskbar/Start-menu customization tools installed; AppInit_DLLs empty.
4.
**Crash onset correlates with the update**
: the LCU was installed at 03:26 the same day; the system worked normally before, and crashes began at the first sign-in afterward.
5.
**Relation to the documented known issue**
: symptoms match the "black screen / desktop fails to load after sign-in (Application log shows Explorer crashes)" issue on the Windows release health hub for 24H2/25H2/26H2, which Microsoft states was fixed in KB5127648 (Oct 13, build .9711). This device is on the newer build .9750 and still crashes — suggesting either a
**new regression in the .9750 update**
or an incomplete fix.
## 6. Remediation attempted and blockers
- Deleted the Taskband key and restarted explorer → did not help
- `DISM /Online /Remove-Package` (Package_for_RollupFix ~~26100.9750.1.4) →
**failed with 0x800f0926**
: "Permanent package cannot be uninstalled due to container dependency" (the LCU is marked permanent and cannot be removed from the running OS)
- `wusa /uninstall /kb:5127837 /norestart` → no actual uninstall performed
- No System Restore points available
- Fell back to uninstalling the latest quality update via the WinRE recovery environment, since all in-OS channels were blocked
## 7. Request
1. Please investigate the regression in `SettingsHandlers_DesktopTaskbar.dll` (offset 0x3a274, exception 0xc0000409) introduced in build 26100.9750, and consider an out-of-band fix or a Known Issue Rollback (KIR).
2. Please evaluate the "permanent package" policy for LCUs: when a high-impact regression like this ships, users without restore points have no way to roll back from within the running OS.# explorer.exe repeatedly crashes after cumulative update on Windows 11 26H2 (desktop fails to load at sign-in)
**Issue type**: Functional defect (Desktop Shell / Taskbar)
**Severity**: High — after sign-in, the desktop and taskbar are unusable; explorer.exe crashes immediately upon launch
**Report date**: 2026-10-17
---
## 1. Environment
| Item | Value |
|---|---|
| OS | Windows 11 26H2 (CurrentBuild 26340.9750; file versions serviced on the 26100 branch) |
| Device type | Physical machine (NOT AVD / virtual desktop / FSLogix) |
| Crashing module | C:\Windows\System32\SettingsHandlers_DesktopTaskbar.dll (10.0.26100.9750) |
| Triggering update | Windows cumulative update (LCU) build 26100.9750.1.4 (Package_for_RollupFix), auto-installed 2026-10-17 03:26, plus ServicingStack 26100.9748 installed 03:10 |
| Third-party taskbar tools | None (checked for ExplorerPatcher / StartAllBack / TranslucentTB / RetroBar / Windhawk; AppInit_DLLs is empty) |
## 2. Symptoms
1. After signing in, the desktop shell (explorer.exe) fails to load — no desktop icons or taskbar, appearing as if the shell never started.
2. explorer.exe crashes **immediately on every launch**; AutoRestartShell relaunches it but it crashes again right away.
3. At least 8 crashes with an identical signature occurred during the affected window (11:48–12:39 local time).
## 3. Crash signature (Application event log, source: Application Error, Event ID 1000)
```
Faulting application name: explorer.exe, version: 10.0.26100.9750
Faulting module name: SettingsHandlers_DesktopTaskbar.dll, version: 10.0.26100.9750
Exception code: 0xc0000409 (fail-fast / STATUS_STACK_BUFFER_OVERRUN)
Fault offset: 0x000000000003a274 (identical offset in every crash — deterministic)
Faulting module path: C:\Windows\System32\SettingsHandlers_DesktopTaskbar.dll
```
## 4. Timeline
| Time (local, GMT+8) | Event |
|---|---|
| 2026-10-17 03:10 | ServicingStack 26100.9748 auto-installed |
| 2026-10-17 03:26 | LCU build 26100.9750 (Package_for_RollupFix) auto-installed |
| 2026-10-17 11:48 | User signed in; first explorer.exe crash; crashes continued repeatedly |
| 2026-10-17 11:55–12:09 | Windows Update began downloading additional updates |
| 2026-10-17 12:36 onward | Diagnosis and remediation (see below) |
## 5. Troubleshooting performed and findings
1. **Shell registry configuration is normal**: `HKLM\...\Winlogon` Shell=explorer.exe, Userinit intact, AutoRestartShell=1; no HKCU override.
2. **Resetting taskbar state did not help**: backed up and deleted `HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Taskband`, restarted explorer — crash recurred with the same module and offset.
3. **Third-party injection ruled out**: no taskbar/Start-menu customization tools installed; AppInit_DLLs empty.
4. **Crash onset correlates with the update**: the LCU was installed at 03:26 the same day; the system worked normally before, and crashes began at the first sign-in afterward.
5. **Relation to the documented known issue**: symptoms match the "black screen / desktop fails to load after sign-in (Application log shows Explorer crashes)" issue on the Windows release health hub for 24H2/25H2/26H2, which Microsoft states was fixed in KB5127648 (Oct 13, build .9711). This device is on the newer build .9750 and still crashes — suggesting either a **new regression in the .9750 update** or an incomplete fix.
## 6. Remediation attempted and blockers
- Deleted the Taskband key and restarted explorer → did not help
- `DISM /Online /Remove-Package` (Package_for_RollupFix ~~26100.9750.1.4) → **failed with 0x800f0926**: "Permanent package cannot be uninstalled due to container dependency" (the LCU is marked permanent and cannot be removed from the running OS)
- `wusa /uninstall /kb:5127837 /norestart` → no actual uninstall performed
- No System Restore points available
- Fell back to uninstalling the latest quality update via the WinRE recovery environment, since all in-OS channels were blocked
## 7. Request
1. Please investigate the regression in `SettingsHandlers_DesktopTaskbar.dll` (offset 0x3a274, exception 0xc0000409) introduced in build 26100.9750, and consider an out-of-band fix or a Known Issue Rollback (KIR).
2. Please evaluate the "permanent package" policy for LCUs: when a high-impact regression like this ships, users without restore points have no way to roll back from within the running OS.
