Microsoft KB4343909 Update Breaks Chocolatey, Triggers Critical PowerShell Module Error

A critical Windows security update has broken the popular Chocolatey package manager, halting installations and updates for countless users. The August 2018 KB4343909 update from Microsoft enforces a new security restriction that causes any Chocolatey operation to fail with a specific, hard-stop error: 'This module uses the dot-source operator while exporting functions using wildcard characters, and this is disallowed when the system is under application verification enforcement.' This error occurs for all packages, rendering the core ChocolateyInstaller.psm1 module unusable on affected systems.

The failure stems from a deliberate change in PowerShell's default behavior, specifically targeting the `Export-ModuleMember()` function when used with a wildcard (*) in conjunction with dot-sourcing. Microsoft's TechNet documentation for the update confirms it 'addresses a vulnerability' related to this pattern, stating that after installation, existing modules on devices with Device Guard enabled 'will intentionally fail.' This enforcement directly conflicts with Chocolatey's helper module architecture, which relies on the now-blocked pattern for function exports.

The impact is immediate and widespread for administrators and developers relying on Chocolatey for software deployment on Windows 10. The update transforms a routine security patch into a systemic operational blocker, forcing a choice between system security posture and automated package management. This creates significant pressure on both Microsoft to clarify enforcement scope and on the Chocolatey project to rapidly refactor its module code to comply with the new, stricter application verification rules.