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ERROR_GRAPHICS_SPECIFIED_CHILD_ALREADY_CONNECTED
Interpret the result in its owning layer: graphics specified child already connected
ERROR_GRAPHICS_SPECIFIED_CHILD_ALREADY_CONNECTED, value 0xC0262400, is produced by child when the child output already has an external device associated with it. The investigation should stay attached to display-child connector occupancy and to the exact generation in which it was obtained.
A child UID identifies an output of the adapter, not necessarily a permanently attached monitor. Presence and descriptor capability must be re-evaluated after hot-plug.
Capture before recreating objects
| Capture item | Why it matters |
|---|---|
| Current graph state | display-adapter child, monitor PDO and connector-presence state |
| Supporting trace | child UID, HPD awareness, monitor descriptor support, PnP events and connector telemetry |
| Object identity | display-child connector occupancy |
| Rejected condition | the child output already has an external device associated with it |
| What to capture | child UID, connector, previous arrival event, monitor PDO and attempted association |
Reproduce one variable at a time
- Capture the failing state. Record child UID, connector, previous arrival event, monitor PDO and attempted association.
- Disconnect the existing child cleanly before associating the test device.
The comparison with ERROR_GRAPHICS_MONITOR_NOT_CONNECTED is especially useful: ERROR_GRAPHICS_MONITOR_NOT_CONNECTED reports the opposite physical state for a VidPN target.
Recovery contract
Deduplicate hot-plug events and maintain one current external device per child connector.
- debug-layer, ETW or driver diagnostics no longer report the rejected display-child connector occupancy contract during the same scenario.
Implementation notes
Log child UID, HPD awareness, monitor descriptor support, PnP events and connector telemetry.
Technical references
- Microsoft: Child device enumeration — background for the display-child connector occupancy.
- Microsoft: Monitor child devices
- Microsoft: Introduction to VidPNs
- Microsoft: Graphics error codes
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