backup applications Archives

Winsage

May 18, 2026

Microsoft confirms Windows 11 security update install issues

Microsoft has acknowledged a significant issue with the May 2026 Windows 11 security update, KB5089549, where users are encountering difficulties in installation, specifically the 0x800f0922 error code. This issue is primarily due to insufficient free space on the EFI System Partition (ESP), especially for devices with 10 MB or less available. The installation may fail during the reboot phase at around 35–36% completion, with users receiving notifications like "Something didn't go as planned. Undoing changes." Log entries may indicate insufficient ESP free space, such as "SpaceCheck: Insufficient free space" and "ServicingBootFiles failed. Error = 0x70." Microsoft recommends affected users utilize the Known Issue Rollback feature to reverse problematic updates and advises IT departments to install and configure the relevant Group Policy to address the issue.

Winsage

May 10, 2026

Microsoft Confirms KB5083769 Breaks Macrium and Acronis Backups

Microsoft's April 2026 Windows security update, KB5083769, may disrupt image-mount operations for backup applications such as Macrium Reflect, Acronis Cyber Protect Cloud, UrBackup Server, and NinjaOne Backup due to the addition of the psmounterex.sys kernel driver to its Vulnerable Driver Blocklist. This action was taken to address a high-severity buffer overflow vulnerability, CVE-2023-43896. The inclusion of this driver in the blocklist has rendered several backup products inoperable, and Microsoft will not retract the block for security reasons. Administrators can use Event ID 3077 in the Code Integrity log to confirm that the blocklist is causing the failures. Microsoft advises updating backup applications to versions that include necessary driver protections instead of uninstalling or pausing the security patch. Additionally, the April updates have caused other issues, such as failures in Windows Server installations and devices booting into BitLocker recovery mode.

Winsage

May 5, 2026

April 2026 Windows Update Breaks Third-Party Backup Software by Blocking Vulnerable Driver

Microsoft will include the psmounterex.sys driver in its Vulnerable Driver Blocklist in the April 2026 security update, affecting third-party backup applications that use this driver for image mounting and Volume Shadow Copy Service (VSS) snapshots. This decision addresses CVE-2023-43896, a critical buffer overflow vulnerability. Affected software includes Macrium Reflect, Acronis Cyber Protect Cloud, UrBackup Server, and NinjaOne Backup on Windows 11, Windows 10, and Windows Server platforms. Users may face issues during image-mount operations, receiving error messages related to VSS timeouts and Code Integrity errors in the Event Viewer. To check if a system is affected, users can look for Event ID 3077 in the Code Integrity Operational log. Microsoft recommends upgrading to newer versions of backup applications that do not use blocked drivers and advises against uninstalling or delaying the April update. Additionally, the update may cause certain Windows Server 2025 devices to boot into BitLocker recovery mode and has led to out-of-band updates for Windows Server update failures and restart loops on domain controllers.

Winsage

May 5, 2026

Defender yanks root certs as Windows updates blocks backups

Microsoft's Defender anti-malware tool update version 1.449.425.0 removed two DigiCert root digital certificates, leading to false positives that flagged them as severe malware (Trojan:Win32/Cerdigent.A!dha). This incident was later identified as a false positive, and updating to version 1.449.430.0 or later reinstates the certificates. The issue may be linked to a DigiCert employee encountering disguised malware. Additionally, Windows updates from April 14 caused third-party backup applications to malfunction due to the addition of vulnerable psmounterex.sys kernel driver versions to a blocklist. Users experienced difficulties with mounting backup image files, and Microsoft referenced a vulnerability rated 9.3 out of 10 in the driver. Other affected software includes Acronis Cyber Protect Cloud and UrBackup server. Microsoft has not explained the delay in adding the vulnerable driver to the blocklist, and other recent update-related issues have also been reported.

Winsage

May 4, 2026

Microsoft confirms April Windows updates cause backup failures

Microsoft has acknowledged that the April 2026 security updates have disrupted the functionality of various third-party backup applications using the psmounterex.sys driver, raising concerns among users. The issue primarily affects software leveraging the Volume Shadow Copy Service (VSS) snapshots, leading to failures due to VSS service timeouts. Notable impacted products include Macrium Reflect, Acronis Cyber Protect Cloud, UrBackup Server, and NinjaOne Backup, used on Windows 11, Windows Server, and Windows 10 devices. Disruptions can manifest as failures to mount backup image files, errors or timeouts when browsing or restoring from backup images, and error messages related to VSS timeouts. Microsoft updated its support documentation to clarify that the April updates included a security hardening change that added psmounterex.sys to the vulnerable driver blocklist to protect against a high-severity buffer overflow vulnerability (CVE-2023-43896). Affected users are advised to upgrade to newer application versions with updated drivers and not to uninstall or pause the security update. Users can check if the Microsoft Vulnerable Driver Blocklist is blocking a driver by looking for Event ID 3077 in the Code Integrity Operational log. Additionally, Microsoft has alerted users that some Windows Server 2025 devices may boot into BitLocker recovery mode after installing the KB5082063 update and has issued out-of-band updates to address installation failures and restart loops affecting Windows Server systems after the April 2026 updates.

Winsage

May 1, 2026

Windows 11’s April update is now breaking third-party backup apps

Microsoft rolled out update KB5083769 for Windows 11 to enhance security, but users have reported issues such as BitLocker lockouts, boot loops, and problems with Remote Desktop functionality. The update is causing compatibility problems with third-party backup applications, including Acronis Cyber Protect Cloud, Macrium Reflect, NinjaOne Backup, and UrBackup Server, due to a bug in the Volume Shadow Copy Service (VSS). Users experiencing backup failures are advised to uninstall update KB5083769 as a temporary solution until Microsoft releases a patch. The timeline for resolving these issues is currently unclear.

Winsage

May 1, 2026

Microsoft fixes Remote Desktop warnings displaying incorrectly

Microsoft resolved an issue affecting the display of security warnings when opening Remote Desktop (.rdp) files across all supported Windows versions, including Windows 11, Windows 10, and Windows Server. This problem was particularly evident on devices with multiple monitors having different display scaling settings. The fix was included in the optional KB5083631 preview cumulative update for Windows 11. The issue arose after the installation of the April 2026 security update, which introduced security warnings to enhance protection against phishing attacks. Users reported misalignment and obscured buttons in the security dialog, making it difficult to interact with. Additionally, the April security updates caused issues with third-party backup applications on Windows 11 systems and led to restart loops and failures during update installations on Windows Server.

Winsage

May 1, 2026

April KB5083769 Windows 11 update causes backup software failures

The KB5083769 security update released in April 2026 has disrupted the functionality of various third-party backup applications on Windows 11 versions 24H2 and 25H2, primarily due to issues with the Volume Shadow Copy Service (VSS). Affected applications include Acronis Cyber Protect Cloud, Macrium Reflect, NinjaOne Backup, and UrBackup Server. Users have reported receiving an error message indicating that backups have failed due to VSS timeouts. Acronis has acknowledged the issue, stating it affects both Windows 11 Pro and Home editions, and warns of potential broader system issues. A temporary solution involves uninstalling the KB5083769 update or pausing Windows updates. Additionally, Microsoft has issued out-of-band updates for critical issues affecting Windows Server systems and warned that some Windows Server 2025 devices may encounter BitLocker recovery prompts after installing the KB5082063 update.