If you get “permission denied” error on one of your files, in a custom folder, make sure to do the following:
chgrp -R youruser customfolder/ chown -R youruser customfolder/
youruser means your username other than root
then you are free from these kinda errors.
In details: I made the mistake of creating a folder with root user, than synced it.
I tried to resolve this issue for 2 or more hours, had to learn about permissions in linux a lot, and thats good, but i hate the fact that i didn’t solve it from google.