Windows – Why does compact.exe suddenly start to compress the disk

compressionwindows 10

I've used Windows 10 since the launch, but the File Compress Utility process(compact.exe) suddenly started to compress my hard disk a few days ago. I didn't touch any settings on the system. Why is this happening at all? It's not just the operating system files, but several folders in my home are compressed, including Desktop, AppData, and .android. Is there a way to know which files are affected so that I can uncompress them?

I enabled Do not allow compression on all NTFS volumes, and also ran compact.exe /CompactOS:never, and the compressing somehow stopped, but it's running again now. Running compact.exe /CompactOS:Query reports it's in the compact state.

Best Answer

This might be caused by KB4023057, which "may take steps to free up disk space on your device if you do not have enough disk space to install Windows updates."

You can uninstall it from Programs and Features, and can block it from installing again using this troubleshooter.