I'm having trouble, too. OSX, Calibre 2.80.0. Metadata source is Amazon.
Title: Deep Navigation
Author: Alastair Reynolds
In the details:
calibre, version 2.80.0
ERROR: No matches found: <p>Failed to find any books that match your search. Try making the search <b>less specific</b>. For example, use only the author's last name and a single distinctive word from the title.<p>To see the full log, click Show Details.
Running identify query with parameters:
{u'identifiers': {}, u'authors': [u'Alastair Reynolds'], u'title': u'Deep Navigation', u'timeout': 30}
Using plugins: Amazon.com
The log from individual plugins is below
****************************** Amazon.com ******************************
Request extra headers: [('User-agent', u'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36')]
Found 0 results
Downloading from Amazon.com took 0.521581888199
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 1169, in identify
File "site-packages/calibre/ebooks/metadata/sources/amazon.py", line 1079, in parse_results_page
CaptchaError: Amazon returned a CAPTCHA page, probably because you downloaded too many books. Wait for some time and try again.
************************************************** ******************************
The identify phase took 0.65 seconds
The longest time (0.521582) was taken by: Amazon.com
Merging results from different sources and finding earliest publication dates from the worldcat.org service
We have 0 merged results, merging took: 0.00 seconds
I did try a large # at once, earlier...