Software issue · Evidence-backed record
Windows black screen after KB5120998 on AVD / FSLogix
Direct answer
Some Windows 11 devices fail to load the desktop after sign-in following KB5120998 or later updates. Microsoft primarily observed this on Azure Virtual Desktop hosts using FSLogix. Workarounds are documented; a full resolution remains pending in the reviewed vendor entry.
Mitigated Microsoft [1] · Microsoft [2]
- Status
- Mitigated FACT
- Affected
- Windows 11 24H2; Windows 11 25H2; Windows 11 26H1; Windows 11 26H2
- First observed
- Unknown
- Last verified
- Confidence
- Vendor confirmed
- Severity
- Unknown
TraceCheck interpretation
Does this explain your situation?
Use these checks to interpret the source. This is a reading guide, not a device test or a vendor diagnosis.
Match the sign-in failure
A black wallpaper with a working desktop is a different symptom. Check the update history and whether the desktop session fails to load before applying this record.
Source: MicrosoftMatch the managed environment
AVD and FSLogix are the primarily observed environment, not proof that every black screen has this cause. Use the vendor policy for the exact Windows version.
Source: MicrosoftMatch the KIR policy to the Windows version
The release-health source separates the 26H1 policy (KB5124006 260924_20071) from the 24H2/25H2/26H2 policy (KB5124010 260924_20021). The KB in a policy name identifies that workaround; it does not establish that installing that cumulative update is a permanent fix for this issue. An administrator must configure the matching policy and restart.
Source: Microsoft
Symptoms
- Black screen after sign-in; desktop does not load automatically. Source: Microsoft
- Application event logs can show Windows Explorer crashes. Source: Microsoft
Affected environments
| Entity | Version | Originating update | Software | Evidence |
|---|---|---|---|---|
| Windows 11 | 24H2 | KB5120998 | FSLogix (primarily observed on Azure Virtual Desktop) | Source: Microsoft |
| Windows 11 | 25H2 | KB5120998 | FSLogix (primarily observed on Azure Virtual Desktop) | Source: Microsoft |
| Windows 11 | 26H1 | Unknown | FSLogix (primarily observed on Azure Virtual Desktop) | Source: Microsoft |
| Windows 11 | 26H2 | Unknown | FSLogix (primarily observed on Azure Virtual Desktop) | Source: Microsoft |
What caused it?
Root cause has not been confirmed.
Fixes and workarounds
No verified remedy is mapped to this version in this record. This does not establish that no remedy exists. Check the vendor's current instructions and your exact environment.
A version match identifies recorded guidance, not a diagnosis or a guarantee. Check the symptom, device and application requirements in each source before proceeding.
Temporarily start Windows Explorer
FACT Official workaround · workaround
Open Task Manager with Ctrl+Shift+Esc, choose Run new task, enter explorer.exe and confirm. This starts the desktop session temporarily; it does not establish a permanent correction.
Workaround — permanent resolution not established
Applies to: Windows 11 24H2, Windows 11 25H2, Windows 11 26H1, Windows 11 26H2.
Risk: low (TraceCheck editorial assessment, not a vendor success rate)
Read Microsoft's instructions ↗Read Microsoft's instructions ↗
Administrator-managed KIR for Windows 11 24H2/25H2/26H2
FACT Official workaround · workaround
For managed Windows 11 24H2/25H2/26H2 devices, administrators can configure the version-specific KB5124010 260924_20021 Known Issue Rollback policy linked in Microsoft release health and restart. This temporarily disables the implicated change until a permanent resolution. The policy name is not a fixing cumulative update, and it must not be substituted for the 26H1 policy.
Workaround — permanent resolution not established
Applies to: Windows 11 24H2, Windows 11 25H2, Windows 11 26H2.
Risk: medium (TraceCheck editorial assessment, not a vendor success rate)
Read Microsoft's instructions ↗Read Microsoft's instructions ↗
Administrator-managed KIR for Windows 11 26H1
FACT Official workaround · workaround
For managed Windows 11 26H1 devices, Microsoft release health links the KB5124006 260924_20071 Known Issue Rollback policy. Administrators must install and configure the policy for this Windows version and restart the device. This temporarily disables the implicated change; a permanent correction remains pending. Do not use the distinct 24H2/25H2/26H2 policy as a substitute.
Workaround — permanent resolution not established
Applies to: Windows 11 26H1.
Risk: medium (TraceCheck editorial assessment, not a vendor success rate)
Current status
Mitigated This is the recorded state as of the last verification, not a live device diagnosis. Microsoft [1] · Microsoft [2]
For the recorded vendor guidance, see Windows release health — desktop loading failureKB5120998 — desktop failure and workarounds.
Evidence
- Windows release health — desktop loading failure
Microsoft · Vendor documentation
Supports: Mitigated status; affected Windows 11 24H2, 25H2, 26H1 and 26H2; AVD/FSLogix context; temporary Explorer launch and distinct 26H1 versus 24H2/25H2/26H2 KIR policies. Permanent resolution remains pending.
- KB5120998 — desktop failure and workarounds
Microsoft · Vendor documentation
Supports: Post-sign-in symptoms, temporary explorer.exe launch, 24H2/25H2 KIR policy and pending resolution.
Change history
- Mitigated
Microsoft records mitigation with a future resolution still pending.
Source: Microsoft