How to properly transfer an SSL certificate to a new server?

Question

Digital certificates

Moved the Thawte SSL certificate to a new physical server. The IP has also changed accordingly. Transferred the .crs and .key files along with the certificate. The server only has nginx. After transferring all this goodness, firefox under XP does not want to be friends with the site, it writes that the connection is untrusted. Everything is ok in other browsers. What other operations need to be done on the server in order for the certificate to work normally everywhere?
The certificate was ordered in 2domains. When I moved to a new server, they just said to transfer the files, there is no need to reissue the certificate and generate new keys.

Answer 1

Everything should be fine. Perhaps the certificate is missing the certificate of the intermediate CA or the cache of the previous SSL session has not been reset.

Answer 2

Another reason is the lack of SNI support. Check the work in IE on WinXP - if it works, then everything is ok. Otherwise, if it is critical that it works on WinXP in IE and the old firelis, then one IP - one domain (without SNI). You can try to update firelis and make sure TLS is enabled

Answer 3

There is absolutely no cache. Specially bare Windows set to check
Both crt and crs.
What about intermediate? I know that they release it somewhere, but in my panel there is only mine and the root one. Contact there to release an intermediate one?

Answer 4

@VasiliyIsaichkin _ I don’t know in what other browsers there may be a problem, it is necessary to solve at the server level. I will not force users to upgrade ...
firefox costs 27. It works in 6 donkeys.