Sometimes this error message will pop up:

Don't panic - it just means the server connection was briefly interrupted. Refresh the page (Press F5 on your keyboard) and the connection should re-establish itself. If it doesn't, you may need to close your web-browser and try again. Make sure to check your internet connectivity too!

If this keeps happening on your machine, you may want to check with your IT team if your system has the updated security certificates and readers. This can sometimes cause a problem in connectivity.