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UI_E_START_KEYFRAME_AFTER_END
Within Windows Animation Manager, UI_E_START_KEYFRAME_AFTER_END reports that the storyboard timing constraints can place a start keyframe after its intended end. Diagnosis of this result should follow the original owner and generation rather than treating the visible symptom as the cause.
Mechanism behind the code
During a this result investigation, Windows Animation is a stateful COM subsystem. Animation variables, transitions and storyboards are created under a manager, scheduled against a monotonic animation time, updated before drawing, and eventually sealed or released., a visible glitch can therefore be downstream of a lifecycle, ownership, timeline, callback, or numeric contract failure.
Keyframes may be related by offsets, transition completion, or other keyframes., the inconsistency can be indirect: each local offset looks valid while the resulting constraint graph reverses the intended order.
The first owner to inspect is the animation manager, storyboard, transition, timer, or callback that returned the HRESULT.
High-value telemetry
| Capture | Diagnostic value |
|---|---|
| Start and end keyframe identities for this HRESULT. | This places the failure on the lifecycle or transaction timeline and helps test the Windows Animation Manager boundary. |
| Dependency edges and offsets for this HRESULT. | This separates caller input from environment and service state and helps test the Windows Animation Manager boundary. |
| Transition durations for this HRESULT. | This provides a stable comparison across retries or another machine and helps test the Windows Animation Manager boundary. |
| Resolved or unresolved schedule times for this HRESULT. | This identifies the exact object or resource generation involved and helps test the Windows Animation Manager boundary. |
Decision table
- Fresh storyboard or animation object: for this HRESULT, a changed result separates retained object, connection, path, host, or device state from the original input. Hold constant: for this HRESULT, keep the timeline, transitions, and manager version fixed.
- Reduced failing operation: If this result follows the reduced step, the rejecting transition is localized. Hold constant: for this HRESULT, retain start and end keyframe identities and remove only unrelated work.
- Targeted corrective control: Use this as a diagnostic branch rather than a blanket workaround: draw the keyframe dependency graph. Hold constant: for this HRESULT, keep the original failing sample available for the final regression test.
Safe reduction procedure
When it is returned, use a disposable control object, repository copy, file, or device association where the subsystem permits it.
- First: Draw the keyframe dependency graph.
- Next: Replace relative keyframes with fixed controls.
- Then: Add constraints one at a time.
- Finally: Assert start time is not greater than end time after resolution.
Do not erase the distinction
During an investigation, UI_E_END_KEYFRAME_NOT_DETERMINED means the end cannot yet be resolved; this code means the constraints permit an invalid ordering.
Do not swap labels without checking which transition depends on each keyframe.
Successful outcome
Verify it with the original scenario, one boundary case, and one deliberate failure; success means the resolved graph preserves ordering for minimum, nominal, and maximum transition durations.
Technical references
The references below define the API family or storage/protocol behavior used to interpret it.
- Microsoft: Windows Animation error codes
- Microsoft: Schedule a storyboard
- Microsoft: IUIAnimationManager interface
- Microsoft: IUIAnimationStoryboard interface
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