Selling main home and moving to second home

Will capital gains apply if I sell my main residence and move into my second home? I understand that capital gains will apply for the second home if sold for the period that it was not lived in as I can only have one primary residence. However, if I have a retirement property and sell my now main home, I am wondering will I pay capital gains on the now previous main residence?

Hi,
As you have 2 properties, you will need to ensure that a nomination is held to confirm which one is your main property for it to be exempt from capital gains -
CG64485 - Private residence relief: only or main residence: two or more residences: right of nomination
Thank you.