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ERROR_PATCH_PACKAGE_OPEN_FAILED
An MSP must first be accessible as a file
ERROR_PATCH_PACKAGE_OPEN_FAILED (1635) is the patch equivalent of MSI open error 1619. Windows Installer could not open the specified .msp file, so applicability and patch transforms may not have been evaluated yet.
Network staging, temporary extraction, security context, and content filtering are common boundaries. In managed deployment, the client may download a patch under one account and invoke the Installer service under another, making a path that existed for the client unavailable during execution.
Isolation steps
- Log the exact absolute MSP path handed to Windows Installer.
- Verify existence, size, and hash immediately before execution.
- Test read access in the elevated service context.
- Move the patch to a stable local staging directory.
- Check whether cleanup code deletes the file while the installer is still using it.
- If the file opens successfully, continue with validity and applicability checks instead.
References
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