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Windows provides notifications to help users identify and fix issues when connecting USB Type-C® devices, chargers, or accessories. These notifications alert users to problems with power delivery, device compatibility, or connection modes. They also guide users toward solutions for better performance and functionality. This article explains the different types of USB-C® troubleshooting notifications in Windows, when they appear, and the technical conditions that trigger them.
Power notifications
The following table describes the notifications that appear in Windows when power-related issues are detected with USB Type-C connections. These notifications help users understand problems such as slow charging, insufficient power delivery, or devices that require more power than the system can provide. Each notification is listed with its typical scenario and the technical conditions that trigger it on different types of systems.
| Notification text | Scenario | Trigger conditions for systems with UCSI | Trigger conditions for systems with custom UCM client driver |
|---|---|---|---|
| Slow charger To speed up charging, use a higher-watt charger. |
User connects a slow USB-C charger. | In response to UCSI command GET_CONNECTOR_STATUS, UCSI PPM returns with both of the following fields. • ConnectorStatusChange.BatteryChargingStatusChange = 1• BatteryChargingCapabilityStatus = 2 (slow charging) or• BatteryChargingCapabilityStatus = 3 (trickle charging)For more information, see USB Type-C slow charging notification requirements. |
The UcmCx client driver calls UcmConnectorPdConnectionStateChanged with the following parameter. • Params->ChargingState = UcmChargingStateSlowCharging or • Params->ChargingState = UcmChargingStateTrickleCharging |
| PC isn't charging Use the recommended charger and cable, and make sure it's directly plugged in. |
User connects a USB-C charger that is too weak to charge the system. | In response to UCSI command GET_CONNECTOR_STATUS, UCSI PPM returns with both of the following fields. • ConnectorStatusChange.BatteryChargingStatusChange = 1• BatteryChargingCapabilityStatus = 0 (not charging)For more information, see USB Type-C slow charging notification requirements. |
The UcmCx client driver calls UcmConnectorPdConnectionStateChanged with the following parameter. • Params->ChargingState = UcmChargingStateNotCharging |
| USB device might need more power Your PC might not provide enough power to the USB device. Connect your device to external power, or try using a different PC. |
User connects a USB-C device which maximum power requirements are greater than what the system can ever provide. | In response to UCSI command GET_CONNECTOR_STATUS, UCSI PPM returns with the following field. • The CapabilityMismatch field (bit 26) of the Request Data Object is set to 1.For more information on Request Data Object, see the USB Power Delivery specification. |
The UcmCx client driver calls UcmConnectorPdConnectionStateChanged with the following parameter. • The CapabilityMismatch field (bit 26) of the Request Data Object is set to 1. |
Mode notifications
The following table lists notifications that appear in Windows when there are issues with USB Type-C connection modes, such as USB4, Thunderbolt, DisplayPort, or other alternate modes. These notifications help users spot compatibility or configuration problems that might limit device functionality. The table also describes the technical conditions that trigger each notification.
| Notification text | Scenario | Trigger conditions for systems with UCSI | Trigger conditions for systems with custom UCM client driver |
|---|---|---|---|
| USB4 device functionality might be limited Make sure the USB4 device you're connecting to is supported by your PC. Select this message for more troubleshooting info. |
User connects a USB4 device to a system that doesn't support USB4. | On the system that doesn't support USB4, the USB4 device enumerates a USB Billboard device with a Billboard capability descriptor which meets both of the following conditions. 1. USB4 mode SVID 0xFF00 is present in the wSVID field. 2. The corresponding entry in the bmConfigure field indicates the mode is not configured (value 0, 1 or 2). |
<- Same as the UCSI systems case. |
| Use different USB port The USB device might have limited functionality when connected to this port. Plug the device into a different USB port on your PC. |
User connects a USB4 device to a USB port that doesn't support USB4, but the system supports USB4 on other USB ports. | On the system that supports USB4, the USB4 device enumerates a USB Billboard device with a Billboard capability descriptor which meets both of the following conditions. 1. USB4 mode SVID 0xFF00 is present in the wSVID field. 2. The corresponding entry in the bmConfigure field indicates that the mode is "not attempted or exited" (value 1). |
<- Same as the UCSI systems case. |
| Thunderbolt device functionality might be limited Make sure the Thunderbolt device you're connecting to is supported by your PC. Select this message for more troubleshooting info. |
User connects a Thunderbolt device to a system that doesn't support Thunderbolt. | The Thunderbolt device enumerates a USB Billboard device with a Billboard capability descriptor which meets both the following conditions. 1. Thunderbolt Alternate Mode SVID 0x8087 is present in the wSVID field. 2. The corresponding entry in the bmConfigure field indicates that the mode is not configured (value 0, 1 or 2). If the USB-C device also supports USB4, its notifications take precedence, or suppress this Thunderbolt notification as long as USB4 mode is configured. |
<- Same as the UCSI systems case. |
| Display connection might be limited Make sure the DisplayPort device you're connecting to is supported by your PC. Select this message for more troubleshooting info. -OR- MHL device functionality might be limited Make sure the MHL device you're connecting to is supported by your PC. Select this message for more troubleshooting info. |
User connects a USB-C DisplayPort or MHL device to a system that doesn't support DisplayPort or MHL over USB-C. | The USB-C DisplayPort device enumerates a USB Billboard device with a Billboard capability descriptor which meets both of the following conditions. 1. DisplayPort Alternate Mode SVID 0xFF01 (or the MHL Alternate Mode SVID 0xFF02) is present in the wSVID field. 2. The corresponding entry in the bmConfigure field indicates that the mode is not configured (value 0, 1 or 2). If the USB-C device also supports USB4 or Thunderbolt, their notifications take precedence. You can suppress this DisplayPort or MHL notification if USB4 or Thunderbolt mode is configured. |
<- Same as the UCSI systems case. |
| USB device functionality might be limited Make sure the device you're connecting to is supported by your PC. Select this message for more troubleshooting info. |
User connects a USB-C device which supports an alternate mode that the system doesn't recognize, and the mode is not configured. As of Windows 11 24H2, only Thunderbolt, DisplayPort, MHL alternate modes, and USB4 mode are recognized. |
The USB-C device enumerates a USB Billboard device with a Billboard capability descriptor which meets both of the following conditions. 1. An unrecognized alternate mode SVID is present in wSVID field. 2. The corresponding entry in the bmConfigure field indicates that the mode is not configured (value 0, 1 or 2). If the USB-C device also supports USB4, Thunderbolt or DisplayPort or MHL, their notifications take precedence. You can suppress the notification for this unrecognized alternate mode when any of these modes are configured. |
<- Same as the UCSI systems case. |
| Use different USB port The USB device might have limited functionality when connected to this port. Plug the device into a different USB port on your PC. |
User connects a Thunderbolt or DisplayPort USB-C device to a USB port that doesn't support Thunderbolt or DisplayPort, but the system supports Thunderbolt or DisplayPort on other USB ports. | 1. In response to UCSI command GET_ALTERNATE_MODES(Recipient=Connector) for each connector, UCSI PPM returns with a list of the alternate modes supported by a connector. 2. When the USB-C device is connected, in response to UCSI command GET_ALTERNATE_MODES(Recipient=SOP), UCSI PPM returns a list of the alternate modes supported by the USB-C device. 3. Triggered when the above UCSI PPM returns indicate all of the following. a. A USB-C device supports Thunderbolt or DisplayPort mode. b. The connected USB-C connector doesn't support Thunderbolt or DisplayPort Alternate Mode. c. There's another USB-C connector that supports Thunderbolt or DisplayPort Alternate Mode. |
Not implemented |
| Unsupported USB-C audio adapter Connect a USB-C digital audio adapter instead. Select this message for more troubleshooting info. |
User connects a USB-C analog audio adapter to a host device that only supports USB-C Digital Audio Adapters | 1. In response to UCSI command GET_CONNECTOR_CAPABILITY for a connector, UCSI PPM returns the following to indicate that audio accessory mode is not supported on this connector. • OperationMode.AudioAccessoryMode = 02. After the user connects a USB-C analog audio adapter, in response to UCSI command GET_CONNECTOR_STATUS, UCSI PPM returns the following to indicate an analog audio adapter is connected. • ConnectorPartnerType.AudioAdapterAccessoryAttached = 1 |
1. The UcmCx client driver calls UcmConnectorCreate with the following parameter. • Config->TypeCConfig.AudioAccessoryCapable = FALSE2. After the user connects a USB-C analog audio adapter, the UcmCx client driver calls UcmConnectorTypeCAttach to report Type-C attach with the following parameter to indicate it supports "USB-C Analog Audio Adapter," • Params->Partner->UcmTypeCPartnerAudioAccessory |