Why are folders and files automatically being compressed in Windows 10?

All the files on my desktop and every file I downloaded from the Internet have suddenly been compressed in Windows 10 (as indicated by two blue arrows on the top right of the icons). I have never set such a setting in Windows. Is this a virus or something else?

My hard drive is 128GB SSD and with 5GB free space.

So why is this happening? Is there an option to turn this behaviour off?

Solution 1:

use this command in cmd to disable compression

fsutil behavior set DisableCompression 1

Solution 2:

I noticed this happening after my upgrade to Windows 10 version 1809 (the October 2018 update) on my 32GB SSD. I usually save my documents in progress on my Desktop before moving them to their permanent locations, and I saw all of my new files getting the two blue arrows. Checking these files' advanced properties revealed that they are indeed being automatically compressed by Windows. None of the policy settings or registry settings to disable compression are preventing this. If I look at the properties for the whole C: drive it shows that automatic compression is off. But if I look at the advanced properties for C:\Users\myaccount\Desktop and C:\Users\myaccount\Documents I can see that they have been set to automatically compress files. If I uncheck this in the two folders (and choose to apply the change to all files and folders under these) then it does seem to stop this behavior, even after a restart.

I can not find documentation for Windows 10 version 1809 that describes the conditions under which Windows starts automatically compressing files without asking the user for permission to do this. It may have been necessary for the update to version 1809 to have enough space to complete the update, but at no point did Windows ASK me if this was OK. It just did it. Normally this would not bother me too much, but one of the identified flaws early in the release of version 1809 was that zipping of automatically compressed files (for example for the purpose of copying/upload files to other locations off of the computer) caused corruption in these files. So the Microsoft developers have obviously made mistakes in released code as far as compression goes.

I seem to recall a recent version of Mac OS X doing a similar thing in which it started encrypting files without asking after a particular update. This trend is not a good one. Again, at least if Windows had ASKED me before doing this then the sudden compression of my files would not have been a surprise requiring me to seek out answers on the Internet.