Here a screenshot (in danish, the english equiv can be seen here https://askubuntu.com/a/187657/107445, similar question but the answers does not solve the problem)
The very weird thing is, that this error only appears when I try to connect to a server from a nautilus opened as system user / gksudo. From a Nautilus opened as "anonymous" user there is no problems connecting to server. I am also able to connect to server from "places".
I have runned
sudo apt-get install gvfs-backends
and as suggested in this similar question https://askubuntu.com/a/187657/107445
sudo apt-get install --reinstall gvfs-backends
sudo apt-get update sudo apt-get upgrade
but still, this error appears, and only appears in Nautilus as system user. Does someone know the answer to this? I am completely stuck.