If you try and download in firefox it spams empty tabs with a local link to the pdf that does not work in the address bar.
In Chrome it works fine.
Solution is simple. Don’t use Firefox.
At work on Ubuntu Firefox I can’t reproduce as well. I can check if it’s an addon later.
What version of Firefox you’re using? What add-ons you’re using?
I just tested my addons and even after disabling them all it still happened.
Firefox 53.0.2 (32-bit) on Windows 10.
Is there anything else I can test?
It might have something to do with Firefox also being my default application to open pdf with? It’s probably a bug on their end.