Microsoft Issues New Guidance Related to USB Type-C Notifications in Windows for OEMs

If USB Type-C notifications aren’t showing up in Windows 11, the issue may not be with the OS itself but with OEM implementation. Over the weekend, Microsoft shared new guidance for manufacturers on how to properly configure and validate these features. Apparently, this will help users troubleshoot problems like slow charging, unsupported accessories, and faulty connections.

According to Microsoft, missing or incorrect ACPI markup is one of the most common reasons. Since Windows relies on ACPI descriptors to identify ports and their capabilities, any mislabeling, such as marking a Type-A port as Type-C, can prevent alerts from triggering.

Similarly, ports incorrectly flagged as internal may suppress notifications even when accessible to users. OEMs are urged to use the Windows Hardware Lab Kit (HLK) to validate USB port descriptors and confirm that _UPC (USB Port Capabilities) and _PLD (Physical Location of Device) ACPI methods are implemented correctly.

Microsoft also recommends stress-testing across charging scenarios, such as using underpowered chargers or USB hubs, to ensure notifications display consistently. Some device makers disable USB data in untrusted environments for security.

Microsoft advises that such policies should only apply to externally accessible ports and that OEMs provide toggles where possible. More importantly, disabling data must not interfere with internal devices like the keyboard or touchpad.

Microsoft’s recommendations include auditing ACPI descriptors across all ports, validating notification behavior in supported scenarios, and coordinating with Windows Hardware Compatibility Program (WHCP) requirements.

Moreover, OEMs are also advised to document exceptions clearly if specific ports or configurations do not support notifications.