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Cloud Sync Engine cloud files search (SearchHandlerFactory) does not seem to work with Explorer

sysadmin 100 Reputation points
2026-04-08T23:03:58.0066667+00:00

The cloud sync engine documentation is pretty clear on this: https://dotnet.territoriali.olinfo.it/en-us/windows/win32/cfapi/build-a-cloud-file-sync-engine#cloud-files-search

I should be able implement IStorageProviderSearchHandlerFactory (https://dotnet.territoriali.olinfo.it/en-us/uwp/api/windows.storage.provider.istorageprovidersearchhandlerfactory?view=winrt-26100) and have Windows Explorer do smarter things when searching my cloud sync engine.

However, what I am finding is that my COM class is never activated - I even used Process Monitor and saw no attempts to read the SearchHandlerFactory registry key.

Also, notably the documentation mentions OneDrive, which itself has a SearchHandlerFactory registered, but I also do not see it being activated or used.

Is this a known issue? Perhaps the documentation was aspirational but doesn't actually work (yet?)

Windows development | Windows API - Win32

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  1. Taki Ly (WICLOUD CORPORATION) 690 Reputation points Microsoft External Staff Moderator
    2026-04-10T08:20:19.0633333+00:00

    Hello @sysadmin ,

    In my validation, I confirmed that OneDrive has a SearchHandlerFactory registration, but in the Explorer search scenarios I tested I did not observe Explorer reading that registration or invoking the associated COM class.

    After reviewing the documentation you shared, I noticed an important support statement in the Cloud files search section: this feature is supported in Windows 11, version 24H2 and later, on Copilot+ PCs or AI-enabled Cloud PCs.

    Based on that, this currently looks more like a support scope or scenario limitation than a registration issue. If the test machine is outside the documented supported environment, that would explain why the handler is not being activated.

    Hope this clarifies your question. If you found my response helpful, please follow this guide to provide feedback.

    Thank you.

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