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NS_E_DEVICE_NOT_READY
What this HRESULT means
Windows Media Player reports NS_E_DEVICE_NOT_READY (0xC00D0FCA) when the referenced device is present or selected but not ready for the requested operation. The device not ready condition is owned by the core that resolves Player.URL, selects or builds a playback graph, chooses codecs and devices, prerolls media and advances between playlist items while reporting asynchronous errors.
The additional test for the device not ready condition is to record device identity, connection state, media presence and underlying device status; that evidence is more useful than reinstalling the Player or changing several unrelated settings at once.
Inputs that distinguish the causes
Preserve the first occurrence before retry or fallback changes the device not ready evidence. The following fields should identify the same object instance:
| Field | What to record |
|---|---|
| What to verify | record device identity, connection state, media presence and underlying device status |
| Artifact identity | selected graph/source/filter or codec identity and version for the device not ready reproduction |
| Runtime state | audio/video device identity and driver generation for the device not ready reproduction |
| Owning object | ordered ErrorItem queue with errorCode, errorContext and media object for the device not ready reproduction |
| Lower-level result | Player.URL, current media sourceURL and resolved final URL for the device not ready reproduction |
| Correlation | play state and transition immediately before failure for the device not ready reproduction |
Do not confuse it with nearby results
| Result | Different condition |
|---|---|
NS_E_WMP_WINDOWSAPIFAILURE | a lower Windows API failed without leaving a more specific error for the WMP wrapper |
NS_E_NO_ERROR_STRING_FOUND | the error subsystem has an HRESULT but cannot resolve a localized description string for that code |
NS_E_WMP_MF_CODE_EXPIRED | the installed Windows Media component is outside the validity window expected by this Player build |
If this result is followed by a broader “cannot play,” “cannot load,” or “operation failed” result, preserve the earlier device not ready event. In the case, the later code can be a consequence from a wrapper, fallback item or UI layer rather than the producing failure.
Investigation order
- Start with the symbolic HRESULT; do not diagnose device not ready from the final dialog alone.
- Record the bytes or object state that produced device not ready before automatic recovery mutates it.
- Exclude a stale callback or superseded object instance as the source of the device not ready event.
- Use this deciding observation for device not ready: record device identity, connection state, media presence and underlying device status.
- Apply the smallest supported remedy for device not ready: bring the same device to ready state before retrying.
Technical references
- Windows Media Player SDK — documentation for this HRESULT.
- Player MediaError event — normative or platform material relevant to this HRESULT.
- ErrorItem object — API or format context.
- Supported protocols and file types — documentation for this HRESULT.
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