What does HRESULT 0xC00D109A (NS_E_WMPCORE_CODEC_NOT_TRUSTED) mean?

Status / error code:

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Constant name:

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Operating System:

Description:

The codec downloaded for this file does not appear to be properly signed, so it cannot be installed.%0

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NS_E_WMPCORE_MISNAMED_FILE	NS_E_WMPCORE_CODEC_NOT_FOUND

NS_E_WMPCORE_CODEC_NOT_TRUSTED

Diagnosing `NS_E_WMPCORE_CODEC_NOT_TRUSTED`

Windows Media Player reports this result (0xC00D109A) when the candidate codec fails the trust/signature policy required for installation/use. The playback core codec not trusted 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.

Evidence that separates the result

Field	What to record
Decisive check	Record codec CLSID, package/signature chain and source
Artifact identity	Player.URL, current media sourceURL and resolved final URL for this reproduction
Runtime state	Play state and transition immediately before failure for this reproduction
Owning object	Selected graph/source/filter or codec identity and version for this reproduction
Lower-level result	Audio/video device identity and driver generation for this reproduction
Correlation	Ordered ErrorItem queue with errorCode, errorContext and media object for this reproduction

Representative case: Automatic codec discovery retrieves an unsigned or altered installer. The example isolates only the producing component.

Nearby results with different boundaries

Result	Different boundary
`NS_E_WMPCORE_CODEC_NOT_FOUND`	The graph cannot find the specific codec required for a media stream
`NS_E_WMPCORE_MISNAMED_FILE`	The file extension/name disagrees with the content or supported media interpretation
`NS_E_WMPCORE_CODEC_DOWNLOAD_NOT_ALLOWED`	The required codec is absent and Player policy/settings prohibit automatic acquisition

Verification

Repeat the original operation with a fresh owning object after the identified precondition is corrected. Treat this result as resolved only when that same operation passes this stage; preserve any later HRESULT as a separate failure.

Technical references

Windows Media Player SDK — documentation used to identify the producing boundary of this result.
Player MediaError event — normative or platform material relevant to it.
ErrorItem object — API or format context for this HRESULT.
Supported protocols and file types It.

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