Someone posted this link in the discussion in the Sony forum:
https://help.overdrive.com/customer/...gital-editions
Here's a copy/paste of the part of the linked page that refers to Sony:
Known issues with Sony Reader, NOOK GlowLight Plus, and Adobe Digital Editions
OverDrive recently upgraded more of our services to HTTPS as part of our continued commitment to security and privacy. While this process was seamless and invisible to the vast majority of users, it resulted in compatibility issues for some older devices and software versions. We apologize for the inconvenience, and have provided solutions and alternatives below (wherever possible).
Sony Reader Wi-Fi
Sony Reader Wi-Fi devices no longer allow users to download library eBooks directly on the device.
Users can still download library eBooks to Sony Reader software on their computer, then transfer eBooks from their computer to their Sony Reader.