Odnoklassniki billing does not work when switching to https, what should I do?

Question

Classmates

Good afternoon!
We had a problem after integrating https - payments do not work.
We use a certificate from startssl, game ok.ru/game/mydragon
Application ID: 216735488 Application
public key: CBAQBMONABABABABA
When accessing the payment script on our server from the portal, the portal has an error (from the billing logs on the portal)
javax.net.ssl. SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
unable to find valid certification path to requested target
We have a valid certification path, at least through the browser you can see the root CA and so on. So it is not clear whether the problem is on our side or not.
Please help me deal with this problem! Payments are not the first day!
Here, by the way, there is a similar question Why doesn't Java accept an SSL certificate?

Answer 1

The problem is on the side of Odnoklassiki, or rather on some of their servers, because basically payments go through, and sometimes this error falls.
We have many applications for OK, payments work in all, and only in one application such an error periodically appears, the certificates were from StartSSL, they thought that the problem was switched to Let's Encrypt, the problem remained.
Here is what I found on this issue
nodsw.com/blog/leeland/2006/12/06-no-more-unable-f...
stackoverflow.com/questions/6908948/java-sun-secur...