What does HRESULT 0xC00D1266 (NS_E_BKGDOWNLOAD_CALLFUNCTIMEOUT) mean?

NS_E_BKGDOWNLOAD_CALLFUNCTIMEOUT

A download-manager operation timed out

NS_E_BKGDOWNLOAD_CALLFUNCTIMEOUT (0xC00D1266) means a task invoked by the Windows Media Player download manager did not return within the time allowed by that operation. It is not the same as a network connect timeout and should not be diagnosed from packet loss alone.

Find the slow callback or operation

Record the function or callback being executed, its start and end timestamps, thread/apartment identity, job ID, and any nested HRESULT produced before the timeout. If a plug-in is involved, capture its version and whether the call blocks on file I/O, COM marshaling, UI work, or another service.

Controlled retest

Repeat the same job with the same source and destination while removing only the suspected blocking dependency. A task that returns promptly after disabling one plug-in or removing one file lock identifies a different cause than a remote server that merely transfers slowly. Do not automatically retry the timed-out callback while the original invocation may still own job or file state.

Technical references

• BITS interfaces and job objects.
• Completing and canceling a BITS job.
• BITS return values and job-state failures.
• Windows Media Download packages.