If you have an iMac with a 3TB drive, and you’ve configured it with Boot Camp, you may get an error when attempting to upgrade to macOS 10.14 Mojave stating “Installation cannot proceed with Boot Camp configured”.

Apple has posted a support article detailing this issue, with options available for affected iMac models.  Some iMacs with 3TB drives have workarounds, and some do not support Boot Camp with Mojave.