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UCEERR_INVALIDPACKETHEADER
UCEERR_INVALIDPACKETHEADER is a Windows User Composition Engine (UCE) HRESULT. It indicates that the composition engine rejected a command packet before it could be parsed because its header is invalid or inconsistent.
What to check
- Capture the preceding WPF rendering exception and the call sequence that led to the failure.
- Check for corrupted process memory, unsafe interop, or invalid serialized composition data.
- Reproduce the issue with a minimal visual tree before changing application rendering logic.
Microsoft guidance for WPF render-thread failures
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