If you want to upvote you have to login again so that take some time. However, Steemit use tool of saving password. So if you like Upvoting some interesting topic just Logout and login fastest because your password has been saved.
This tool is working in all uses of site such as posting, commenting etc.
you will get this message every time you try to do some of functions I have talked about.
TypeError: Cannot read property 'get' of undefined