Upgrading CyanogenMod versions
This is something that drives me absolutely nuts. People run around telling users that they should be wiping data between rom upgrades. I'm not talking about between nightlies, although I've even seen that recommended before which is insane, but between major version upgrades. There is no reason you should have to wipe your data when going from cm-12.1 to cm-13.0. Database migrations are built in to the rom. It handles the upgrade for you. People like +Adnan Begovic
spend a bunch of time making sure this sort of stuff works.
99% of the time if someone is having issues after a major release upgrade, its because they didn't flash an updated gapps package along with the rom (not something CM really has any control over) or they went backwards (cm-13.0->cm12.1 for example) as migrations don't handle a downgrade.
On several occasions I've seen +Abhisek Devkota
mention that if we do something that forces a user to wipe their data, we've done something wrong. That couldn't be more true.
Now, if you're lucky enough, you may be able to get your hands on an early unofficial build of cm 13 for your device. These most likely will require a wipe at this time, as the database migrations are still in development. But by the time official nightlies start, they will
This is on par with the "wipe your data 3 times in recovery to make sure you get it all" rumor. tl;dr
You don't need to wipe your data when you upgrade to an official cm-13.0 build and anyone that tells you different is misinformed, ignorant or just plain lying to you.