Urgent! Help! Problem with SSL. Checkout doesn't work when using SSL and CloudFlare!

version 4.60.6

I have added my site to CloudFlare to use SSL.
Everything works fine, but checkout doesn't work. Just after going to checkout it redirects back to cart page.

I have inspected and figured out this issue:
Mixed Content: The page at 'https://site.com/onepagecheckout#opc-billing' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://site.com/checkout/OpcSaveBilling/'. This request has been blocked; the content must be served over HTTPS.

I tried to switch on
UseProxe: true,
force SSL,
domain in admin settings set to https://

I tried almost everything what was recommended on forums!

Nothing helps!

How to solve this??? Please help!

It just uses the store location to create the url
                        Billing.init('#co-billing-form', '@(storeLocation)checkout/OpcSaveBilling/',

Do you have https://site.com/ in you store settings ?

Yidna wrote:

It is set to https://mysite.com/

It doesn't help.

How to solve this?

1. is your server is vps server ?
2. if vps then you added self-signed certificate into your IIS ?

forefront wrote:

Yes, it is VPS. I checked it. It has certificate.

This one:


Do I have to delete it?