Why Your Backups Are Suddenly Failing After Windows Updates
If your backup jobs started failing after recent Windows updates, you are not alone. Microsoft’s April cumulative update KB5083769 added the kernel driver psmounterex.sys to the Windows Vulnerable Driver Blocklist to close a high‑severity buffer overflow (CVE-2023-43896). That driver is widely used by backup vendors for image-mount operations, so blocking it has caused a wave of Windows update backup failure issues across Windows 10, Windows 11, and Windows Server. Image creation may still complete, but image-mount and snapshot operations can fail with VSS snapshot timeouts or VSS_E_BAD_STATE errors. Administrators can confirm the root cause by checking Event Viewer’s Code Integrity log for Event ID 3077 showing psmounterex.sys was blocked. This is not a simple application bug; it is a deliberate security enforcement change in the kernel that directly impacts Macrium Acronis compatibility and other backup tools that depend on the same driver.
Which Backup Tools Are Affected and How the Driver Blocklist Breaks Them
The psmounterex.sys block hits multiple enterprise and SMB backup platforms because they integrated the same shared mounting driver. Microsoft has specifically identified Macrium Reflect, Acronis Cyber Protect Cloud, UrBackup Server, and NinjaOne Backup as products that may fail when performing image-mount tasks on systems with KB5083769 or related cumulative updates installed. In practice, backups may appear to run, but operations that need to mount or manage disk images silently fail when Windows refuses to load the blocked driver. This kernel driver blocking is enforced through App Control for Business policies and is part of Microsoft’s broader effort to stop bring‑your‑own‑vulnerable‑driver attacks, where signed but exploitable drivers are abused for local privilege escalation. The result for administrators is a dangerous gap: backups look healthy at a glance, while restore testing reveals that critical image operations no longer function as expected.
Immediate Workarounds for Backup Failures Without Sacrificing Security
Because psmounterex.sys contains a serious privilege‑escalation flaw, Microsoft is unwilling to remove it from the Vulnerable Driver Blocklist, so simply uninstalling the April update is not recommended as a long‑term fix. Instead, Microsoft advises customers to update their backup software to newer builds that replace psmounterex.sys with a hardened, non‑blocklisted driver. Vendors including Macrium, Acronis, UrBackup, and NinjaOne are preparing such builds, but many environments need relief now. As a temporary workaround, you can roll back KB5083769 or pause Windows updates on affected systems, but only after assessing the risk of running without the latest security patches. In all cases, you should perform a full test restore of critical backups to confirm they complete successfully. Document which machines are impacted, monitor Event ID 3077, and plan to reapply the security update as soon as compatible backup versions are available.
Dell SupportAssist Remediation Causing BSOD Crashes and Reboot Loops
A separate but equally disruptive issue is hitting Dell users. SupportAssist Remediation version 5.5.16.0, released on April 30, is triggering frequent blue screen crashes with CRITICAL_PROCESS_DIED errors on systems like the XPS 15 9530, Precision 3571, and Dell Pro Plus 14. Users report their machines crashing and rebooting roughly every 30 minutes, turning routine work sessions into constant recovery battles. Community members using WinDbg traced the problem to DellSupportAssistRemediationService.exe, and noted that crashes stopped once the service was removed or disabled. This pattern mirrors earlier SupportAssist problems documented in January 2025 threads, suggesting a recurring reliability gap in Dell’s remediation stack. Unlike the backup driver issue, this is not a security hardening measure but a faulty OEM tool that destabilizes Windows, further complicating the already delicate balance between automatic maintenance utilities and system stability.
How to Stabilize Your Systems and Prevent Future Conflicts
There are straightforward steps to restore stability while vendors ship permanent fixes. On Dell systems suffering from the Dell SupportAssist BSOD crash, you can open an elevated Command Prompt and run a service configuration command to disable “Dell SupportAssist Remediation,” then restart. Alternatively, uninstall SupportAssist Remediation and the OS Recovery Plugin via Control Panel, preserving normal operation until a corrected release arrives. For backup failures, avoid blindly disabling security features; instead, coordinate with your backup vendor for updated builds that no longer rely on psmounterex.sys. In the meantime, adjust maintenance windows, test restores regularly, and consider staged rollouts of future Windows updates rather than automatic, same‑day deployment across all endpoints. Both incidents underline a shared lesson: automatic updates to low‑level tools and drivers can conflict with essential system utilities, so change control, monitoring, and validation are critical parts of any update strategy.