# Run File Extraction Functions Out of Process

The out-of-process setting specified when you create the Filter object or in the `formats.ini` is automatically propagated to the File Extraction API. When you extract subfiles from container files and pass the files for filtering out of process, Filter generates a server called `kvoop.exe` for filtering and a duplicate server also called `kvoop.exe` for file extraction. These servers are independent, so if the filtering service stops responding, the file extraction service can continue extracting files uninterrupted.

## Restart the File Extraction Server

If the file extraction server fails on a file and throws the exception `KVError_InvalidOopDriverSignature` or `KVError_InvalidOopServiceSignature`, you must restart the server by recreating the Filter object, and process the source file again.

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