Cannot access plus.google.com
I got a 404 error when trying to open that link.
But access to plus.google.com/+VivaldiBrowser seems normal.
Thus only the homepage of Plus is problematic.
I cleared all cookies, still same result.
I disabled Chromium PDF view plugin, still same result.
I disabled the Fedora User Agent Extensions, then it loads a redirected link: https://plus.google.com/collections/featured
(This redirection happens when no logon cookies are there)
After first logon, it loads my G+ profile page correctly.
Is this a problem from Google+ side or from the FUA Extension side?
Like in https://forum.vivaldi.net/topic/14627/plus-google-com-404
Try to open it in Private Window.
The behavior seems the same here.
Only that the Fedora User Agent is installed by dnf automatically. I did not install any manually.
Your suspicion seem correct.
I change my user agent to have Fedora in it, with "Fedora User Agent" I grabbed from the Store.
Mozilla/5.0 (X11; Fedora; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.89 Safari/537.36 Vivaldi/1.8.770.25
Bam, https://plus.google.com... 404.
It's Google's buggy sh...site. The extension is part of the normal Workstation install of Fedora. After (re)installing Fedora, I usually remove everything I don't need because it shovels a lot of cruft on the hard drive.
I think it's Fedora fault. It installed that extension which inject illegal name to useragent.
Google just puke on it.
I agree it is Fedora's fault.
It surprises me when I asked at Google+ Help page, it seems no one ever reported this to their end.
Oh yes. I do find post that seems yours in G+.
May be most users in Fedora not use Chromium beta & G+ at same time.
I only past 1 issue talking about this, it only said will be fix in next version of that extension.