I’m not too sure anymore what exactly this error is but it’s one of the following:
a) This error occurs when you try load the site with an (now) invalid session.
E.g. when your browser tries to safe your sessions so you don’t need to re-login every time you start the browser the stored session key is now invalid and you receive this error.
or b) When you are loged in already and then resending the login form the session is rejected.
not sure i go direct to log in screen ha it a few times on my phone and pc unsure whats going on
As far as I am aware this happens if you wait for too long on the login screen without actually logging in, and then try to login later. You can try opening the page and logging in straight away and it should be fine. Conversely if you open the page and leave it for 15 mins or so and then login you get the issue.
There is the potential for it to not be what I just described, but if you try that first and then let me know what happens for you, we can skip to the next fix if it’s not that.