When trying to activate an old copy of Divi Booster, you may get the following error:

Error: Unknown SSL protocol error in connection to divibooster.com:443

This post provides information on why this issue is happening, and what to do about it.

What is the Problem?

I secure all connections to Divi Booster with HTTPS (i.e. connections are encrypted), including license key activations. When your copy of Divi Booster tries to activate the licence key, it first tries to agree with my server on the type of encryption to use.

My server requires the encryption to use at least TLS1.0, as all earlier encryption protocols (i.e. SSL1-SSL3) are considered insecure. Unfortunately some web hosts only support these earlier, insecure protocols and do not support TLS1.0. The result is that your WordPress and my server are unable to find a mutually acceptable encryption protocol and the connection is rejected with an error, rather than the license being activated.

What can be done about it?

I've actually now removed license keys in recent versions of Divi Booster, so if you're getting this issue the easiest way to deal with it is to manually download the latest version of Divi Booster and then install it on your site (removing your older copy). Your Divi Booster settings will be remembered, and your site will now be ready to receive automatic updates without any need to activate a license key.

Another solution to this issue is to update your web server to support the TLS1.0 encryption protocol. Note that this will most likely require action on the part of your web host and unfortunately, it will not always be possible to persuade your web host to do so.