Candidates sometimes have the wrong idea about the viva.
They expect that they’re an inch away from failure.
They think it could be a lawless free-for-all where examiners can do and ask anything.
They sometimes believe it’s a terribly high bar to clear, that too much will be demanded from them.
Or they sometimes think that because most candidates pass that the viva itself is a trivial exercise.
There are lots of ways you could get the wrong ideas about the viva. The simplest way to find some right ideas is to learn more. Don’t build your ideas of the viva on doubts, worries and half-truths. Learn about what they are like. Ask people who have passed, rather than rely on rumours. Read the regulations. Talk with your supervisors.
The right ideas about the viva will give you a sense of what to expect, what happens in your department and institution, how people experience them – and give you right ideas for what you can do to get ready.