After install the new version Firefox shows this error on almost all sites.
Workaround:
Set to false network.http.spdy.enabled.http2 preference in about:config

It needs nss/nspr currently in the build repo, will move both asap.
Better workaround is to install nss & nspr from the build repo 🙂

Awesome job as always. Thanks, demm.

Both nss & nspr are now up in the stable repos, new pacman -Syu will fix the Firefox issue.