Contents
Controlled Folder Access is a feature introduced in Windows 10 Fall Creators Update released in October 2017. It is designed to protect your folders with some important data (for example, documents) from unauthorized changes performed by untrusted, unwanted programs or malware (encryptors in particular).
When the feature is enabled Windows 10 will block access to your sensitive data if the app accessing files in a protected folder is not considered as trusted or its behavior seems to be suspicious in some way. Here is how to enable it in Windows 10 and enable protection of your most important folders.
Enable the Feature
Before you turn to setting up the feature ensure you have Windows Defender enabled on your computer. Read the last paragraph in this article about how to quickly enable it.
- Double-click the Windows Defender Security Center icon in the taskbar:
- Go to “Virus & threat protection”.
- Click on “Virus & threat protection settings”:
- Enable Controlled folder access:
Once you’ve this, Windows Defender will block each attempt of untrusted program to modify folders you’ve selected. 
Add Protected Folders
You can add your other folders with some important data so Windows will be protecting them too. Click on “Protected folders” and add other folders: 
How To Add Allowed Apps
You may encounter the situation when Virus & threat protection blocks the program you trust: 
In this case you can add it to the allowed apps list. Click on the “+” icon and browse to the program you wish to add to exclusions: 
Once you’ve done it Windows 10 won’t block the app anymore.
Precautions
Do not try to add everything to “Protected folders”. Especially it is not recommended to enable controlled access for system folders such as C:\Windows, C:\Program Files, C:\ProgramData. Use the feature exclusively to protect your documents, projects, etc.