I'm getting an invalid certificate warning when I visit owncloud.org to download the desktop client: Image. I naturally tried another browser, but they use the same certificate store on Windows. I cleared the SSL state and closed and reopened all browsers and it still shows the same warning.
I'm getting this response too. I'm using firefox 48.0.2.
I've reported to sysadmins, sorry for the inconvenience.
Fixed this now. The letsencrypt agent did not renew correctly.