Update on this for me. A few days after my last post on this it cleared up and worked fine. Without me doing anything. About 4 days ago it started doing it again. The error message for amazon indicates a captcha field blocking the query.
****************************** Amazon.com ******************************
Request extra headers: [('User-agent', u'Mozilla/5.0 (Windows NT 6.1; Trident/7.0; rv:11.0) like Gecko')]
Found 0 results
Downloading from Amazon.com took 0.408433914185
Plugin Amazon.com failed
Traceback (most recent call last):
File "site-packages/calibre/ebooks/metadata/sources/identify.py", line 48, in run
File "site-packages/calibre/ebooks/metadata/sources/amazon.py", line 1163, in identify
File "site-packages/calibre/ebooks/metadata/sources/amazon.py", line 1073, in parse_results_page
CaptchaError: Amazon returned a CAPTCHA page, probably because you downloaded too many books. Wait for some time and try again.
************************************************** ******************************
I find the message confusing based on number of books. I have been able to do 100 to 200 books at the time with no issues other than individual books it was unable to identify. Other times a single book will give this message. I have thought maybe it had something to do with sometimes running through my vpn service that could have thousands of other users using that ip and to many of us collectively are doing similar requests. However I can disconnect from the vpn and get identical results/errors.
The error makes me think it is a amazon security feature causing the problem. However it seemed to start and end not long after I respectively updated calibre in both instances. Take this feeling with a huge grain of salt though as it's only worth the digital ink im printing it with
