This error is affecting me as well. Even when closing For Honor through the task manager, it will continue to be on in the background and won't shut down unless I reboot.
I'm having this problem, as well. It's not serious (as long as it doesn't corrupt my save data), but it's still annoying. I'm constantly having to open Windows Task Manager and force For Honor's process to end. I hope this gets fixed soon.
Thanks everyone, we have this listed as a known issue. As others have mentioned, the current workaround is to close using task manager if this happens, but we'll hopefully have a fix for this as soon as possible.