What does NTSTATUS 0xC01E0314 (STATUS_GRAPHICS_MODE_ALREADY_IN_MODESET) mean?

STATUS_GRAPHICS_MODE_ALREADY_IN_MODESET

Mode-set membership is the condition being checked

A mode set is a collection owned by a VidPN source or target. This status means a mode with the same identity has already been added to the selected set. It does not mean the current desktop mode is active, and it does not imply that a monitor rejects the mode.

Duplicate mode insertion often comes from merging lists supplied by multiple discovery paths, repeated callback handling, or failing to replace an old set with a newly constructed set. Treat the mode set as a set, not an append-only history.

Fields to capture

• Log the mode-set handle and a canonical representation of every inserted mode.
• Check whether the driver is rebuilding a new mode set or appending to one retained from an earlier enumeration.
• Compare with STATUS_GRAPHICS_MODE_NOT_IN_MODESET, which is a lookup failure rather than a duplicate insert.

References

• Microsoft: VidPN objects and interfaces
• Microsoft: Cofunctional mode enumeration