Overdrive, one of our two eBook vendors, limits the number of eBooks that can be returned early within a short period of time. If you exceed that number, the system will block you from checking out or returning additional eBooks for a period of time.
If you get an "Early Return Error" on an ebook, wait a day or two and try again. The length of that lockout time depends on how early and how many titles have been returned early. During that time you should still be able to check out audiobooks. We regret that we are unable to tell you exactly how long you will be blocked.
Please submit a Support form ( https://library.carr.org/forms/dig_supp.asp ) if the problem continues.