CardBook 30.6 standalone: WARNing and (NS_ERROR_FAILURE) for TbSync
I [John Bieling] also observed something VERY strange. I am on TB 52.9.1 with lightning 5.4.
If I execute StandAloneCardBook, lightning gets upgraded to 6.2, which causes TbSync to fail (because not compatible). The error you report happens on a line during shutdown, where observers are removed. If Tbsync fails to load during startup, those observers are not added. So this looks plausible.
Could you try to disable lightning on your system and try again?
https://github.com/jobisoft/TbSync/issues/116#issuecomment-416900981
Edited by ChriZilla