If you have the necessary permissions and roles allowing you to publish to Facebook or you have published to Facebook previously, and get an error when trying to publish to Facebook, follow these steps. If this is your first time attempting to publish to Facebook, please reference this article for steps to get started.
If you receive an error message similar to the below:
It's a simple fix. Please disconnect from Facebook and re-connect and you should be all set.
Note, Facebook may suspend publishing when you've exceeded 500+ custom audiences. Delete some of your inactive audiences from Facebook and you should be good to go.
Lastly, make sure you are following Facebook's Advertising Policies.