The name of the file (letters and numbers) is changing.
Vivaldi 1.7.735.46
Does avast also alert if you download with another browser ?
There is no problem with auto update.
Also, there is no warning with Firefox.
Weird.
Check alerts for this → /assets/js/script-29e68965.js
and https://html5shiv.googlecode.com/svn/trunk/html5.js separately.
Re: https://nl.pagespeed.de/webseite/ssl/vivaldi.com
But probably these blocked IPs are causing the alert: List of referenced blacklisted domains/hosts: 2
1.0.435.46
1.7.735.46
Would be nice if we could get this affirmed from an Avast Team Member,
polonus (volunteer website security analyst and website error-hunter)
Hi,
The file I downloaded from https://downloads.vivaldi.com/stable/Vivaldi.1.7.735.46.exe: https://www.virustotal.com/en/file/62a624ab2a9fffd806d4d28c509fac522f19e6e32cd1911e7bf2c83b7c60c142/analysis/1486564036/ was detected by evogen (and it was a false positive). (Also, I got the warning with my firefox 
)
I added the file on our cleanset and will add the digsig to our cleanset as well 
Thanks for reporting it!