Microsoft: Some Windows servers enter reboot loops after April patches

Microsoft has identified a bug in its April 2026 security updates causing Windows domain controllers to enter continuous reboot loops. This patch-related issue affects critical infrastructure components, potentially causing significant service disruption and downtime for organizations relying on Active Directory services. Microsoft is investigating the root cause and is expected to release corrective guidance or a hotfix. Organizations should test patches in non-production environments before deployment and maintain backups of domain controller configurations. This incident highlights the risks associated with automated patching of critical systems without adequate testing procedures.

Microsoft warns that some Windows domain controllers are entering restart loops after installing the April 2026 security updates. [...]

Microsoft has identified a bug in its April 2026 security updates causing Windows domain controllers to enter continuous reboot loops. This patch-related issue affects critical infrastructure components, potentially causing significant service disruption and downtime for organizations relying on Active Directory services. Microsoft is investigating the root cause and is expected to release corrective guidance or a hotfix. Organizations should test patches in non-production environments before deployment and maintain backups of domain controller configurations. This incident highlights the risks associated with automated patching of critical systems without adequate testing procedures. Microsoft warns that some Windows domain controllers are entering restart loops after installing the April 2026 security updates. [...] Microsoft warns that some Windows domain controllers are entering restart loops after installing the April 2026 security updates. [...]