How to install pfx certificate on customer domain.

re;

You already have it (CA bundle). Only the CA root certificate is missing in the chain. What is your certificate provider and type?

BTW: I would recommend you to update to latest branch again (bugfixes reasons)

Re;

So, to summarize:

• Add the private key in the private key input field
• Add your certificate in the certificate input field (the certificate located bellow the private key)
• Add any other certificate in the CA bundle input field
• Add the root certificate at bottom in the CA bundle input field

And please, update your i-MSCP because some bug were fixed (including SSL)

Re

I'm not sure about the root certificate. I must know what certificate type you have from GeoTrust.

Look there https://www.geotrust.com/resources/root-certificates/

If you don't known, just put the last certificate you have in you file here: https://www.sslshopper.com/certificate-decoder.html and post us the result.

Please, put the the last certificate (including tag) from your file here https://www.sslshopper.com/certificate-decoder.html and post the result.

Thanks

Re;

So try to add the following certificate at bottom of your CA bundle (after other intermediate certificate)