How to reset iTunes backup configuration for iPad and iPhone?

Question

After buying a new Mac, I migrated my settings (because there were w a lot of apps) and generally everything's working. Except when I try to sync my iPad or iPhone, I get the following error:
iTunes could not backup the (device) ... because the backup was corrupt or not compatible with the iPad
A few notes
It does work with a new account, just not this one, so there's some setting somewhere that probably needs to go
I did repair disk permissions
I tried to reset preferences via mv *iTunes* to a backup folder in <user>/Library/Preferences
There are no backups on this machine (if you go to iTunes / Settings / Devices the "device backups" list is empty)
It still feels like something is pointing somewhere invalid, but I have no idea how to reset it.

Answer 1

The problem turned out to be a symlink to a folder that pointed nowhere where the backups were stored.
I seriously doubt many people are going to run into this issue, but hey, there you go, another thing to watch out for are symlinks if you transfer your settings to a new machine.
The reason before was that I was clearing out space on a SSD, and backups took up enough room.