What does HRESULT 0xC00D10A2 (NS_E_WMPCORE_PLAYLIST_ITEM_ALTERNATE_MORPH_FAILED) mean?

NS_E_WMPCORE_PLAYLIST_ITEM_ALTERNATE_MORPH_FAILED

The exact condition behind the dialog

NS_E_WMPCORE_PLAYLIST_ITEM_ALTERNATE_MORPH_FAILED is HRESULT 0xC00D10A2. At the playback core playlist item alternate morph failed checkpoint it means the core cannot switch the active media object into the selected alternate representation; the result belongs to the Windows Media playlist and metafile state machine, not to an unspecified Player failure.

An additional test is to record active media state, selected alternate, transition point and the first morph-specific failure; that evidence is more useful than reinstalling the Player or changing several unrelated settings at once.

How to prove the condition

1. Preserve 0xC00D10A2, the ErrorItem context and the object instance involved in playback core playlist item alternate morph failed.
2. Confirm the failure directly: record active media state, selected alternate, transition point and the first morph-specific failure.
3. After you rebuild the alternate as a compatible media object or restart the item transition cleanly, recreate the owning WMP object and verify that the corrected generation completes.

Minimum useful incident record

Capture state before Player cleanup:

• What to verify: record active media state, selected alternate, transition point and the first morph-specific failure.
• Artifact: repeat/event state and the media object expected at its start or end.
• State: playlist URL, format, response content type and exact downloaded bytes.
• Object identity: ASX version and element stack at the failure.
• Underlying evidence: resolved base URL for REF or ENTRYREF targets.
• Correlation: current item index, alternate index and nested-playlist depth.

Why the producing component matters

Before changing state, remember that Windows Media metafiles are XML documents, but a well-formed document can still violate required ASX element and attribute rules. A second platform rule is that relative references are resolved against the containing metafile URL, and nested playlists introduce a stack and a new base URL rather than a simple flat list.

Representative case: The alternate is known, but changing the live item from its primary representation fails.

Targeted fix

Change the responsible precondition rather than masking the symptom: rebuild the alternate as a compatible media object or restart the item transition cleanly.

Neighboring codes to separate

Completion criteria

Keep one fixture that reproduces 0xC00D10A2 and one corrected fixture that changes only the identified precondition.

Technical references

• Windows Media metafile reference — API or format context.
• Metafile elements reference — documentation for this result.
• ENTRYREF element — normative or platform material relevant to this result.
• REPEAT element