Adobe Digital Editions quitting unexpectedly

Adobe Digital Editions is quitting whenever i connect my Kobo eReader to my Mac computer. This problem only commenced recently. (I have had no problem previously.) My Kobo Aura H20 software is up to date. ADE on my computer was version 4.4.7 when the problem commenced. I downloaded ADE again in case it was not the most current version, and the version that downloaded is 4.5.10). But the problem continues. I have tried closing and restarting the computer and reversing the order in which I plug in the Kobo reader and open ADE. But ADE continues to quit. My computer is Mac OS Sierra. Can anyone please help, or even identify if the problem is caused by ADE or my eBook reader?