Airbnb listing detail settings include your listing title, amenities, description, number of guests, Wifi instructions, house manual, and more.
If you receive an error message when trying to save a change for any of these settings, it is most likely due to your listing title being over Airbnb's character limitation. Due to a change made by Airbnb, any update to the listing details will trigger an error if the listing is over their character limitation: 50 characters total for the listing title plus listing nickname.
In order to resolve this, follow the instructions here to edit your listing title and/or nickname so it is under 50 characters total. You can then proceed with the other detail changes as needed.