Unable to deal with captcha.

[leovan]

It seems that we need enter captcha sometimes to download the PDF from sci-hub.

[ziofat]

Captcha image did not show up.

[leovan]

Thanks for report. I tried with this case, actually the response of fetching the pdf is not the page with captcha. Since the response is an HTML and it also has an <iframe>, the <iframe> is also an HTML (which was used to determine whether we need give the captcha or not). But the truth is that in the <iframe> is an HMTL, yet not the CAPTCHA page. I tried with sci-hub.tw too, it leads me to another page to download it (https://sci-hub.tw/https://epjdatascience.springeropen.com/articles/10.1140/epjds/s13688-018-0146-8) and it seems an OPEN ACCESS articles. So I think I can't handle all scenarios of different external websites. I think I can enhance the log output, which may help user to download manually. And I will fix this later in next release.