Folder error in contacts 'Friends' and 'friends'

[Google Contacts] Creating or updating folder ‘xxxxx@gmail.com/Contacts/Friends’ failed due to the following error: Cannot modify a system group.

Contacts contains two folders: “Friends” and “friends”. Cannot eliminate either folder and this circumstance results in the error message above.

Any suggestions?

You may be able to remove one of them (probably friends) in the Google Contacts web interface.

Otherwise you can’t change system folders because the server doesn’t allow that.

Right-click on the Contacts folder and choose Properties > Repair > Repair.
This will force a resync of all the contact folders and the error will go away.
Initially the folders may appear empty, but they will repopulate after the sync or a restart.