We have just released a CB nightly with the newest official Mozilla list of CA certificates from yesterday as well as with a small fix in Guzzle. Please also test that (CB nightly is in our Downloads menu area here).

CB Antispam using ReCaptcha with CB 2.1.1 works fine also on our demo site here, so it seems to be a particular server config that stopped working. So access really appreciated (unless you can confirm that the latest nightly fixes the issue?)

CB nightly (latest) is already default choice on our downloads menu www.joomlapolis.com/downloads and can be downloaded with the Download button on its right. Then install it as a normal Joomla extension (it will update the 2.1.1 version you have). Of course, backup first if it is a live site.

Ubuntu 14.04 LTS that we use on our demo server and here is not affected, and I have no CentOS box to test. If needed could setup one or get a hosting account on such a box, but it doesn't mean that it's only OS related, it must have to do with the openssl or server certificates configuration. So I think it's faster to have access to a failing server.

But here are the first 2 tests that I would like to do that you can also do and give feedback:

1. Download and install the nightly (pkg_communitybuilder_2.1.1+build.2017.01.20.01.24.41.b5adb972f.zip) and see if it fixes it.

2. If not, download the stable version 2.1.0 (in version drop-down choose pkg_communitybuilder_2.1.0+2016.12.18.16.28.40.cb77dc626.zip and click download button on the right of Community Builder package in our downloads, then DO NOT install it in Joomla, but unzip it, in there unzip com_comprofiler.zip and in there use the file libraries/CBLib/GuzzleHttp/cacert.pem to replance the same file on your site, then test again if it now works.

EDIT: Fixed post to take cacert.pem file from 2.1.0 and not 2.1.1.

sbubb wrote: An update to my first post.

On a test site using CB 2.0.15 and antispam 2.0.0+build.2016.05.17.02.30.46.611c15f88
Can register a new user and do not get errors.
If I upgrade just CB to 2.1.1 and antispam plugin is still at old version I now get this cURL SSL error?

Appear to be a change to CB core??

Yes, CB core HTTP library and certificate has been upgraded. Please try the 2 trials I gave above (1. installing latest CB nightly, 2. test, 3. if fails, take the previous CB 2.1.0 (NOT 2.1.1) cacert.pem file to replace the one of nightly).