Each file and folder that resides on your web server side includes a set of permission. These set of permissions are read, write, and execute. These permission are assigned to your folders and files to help your website run as expected and with error free.
Read: This attribute tells if the folder or file is readable by the server.
Write: This attribute tells if the folder or file is writable by the server.
Execute This attribute tells if the folder or file is executable by web server.
If the file and folder permission your site is not set properly, then your website might stop functioning as expected.
So you need to change the file and folder permissions correctly.
Change Your File And Folder Permission From Filezilla Client
Open Filezilla and login to you account
Select a file or directory which you want to change the permission. If my case my folder is wwwroot/.
Click on a file or folder Click on File Permissions.
Now click the checkbox carefully to select the permission you want or you may enter 755 directly, This will change permission to read/execute by everyone, but only writeable by the file/folder owner.
Step 5 :
Click OK and now you are done.