How to import CA into easy-rsa?

Question

openvpn

Certificates were created for ca clients and openvpn server. After that, I reinstalled Ubuntu, after copying the keys folder with all the certificates and keys. How can I generate a certificate and key for another client using them. I tried to create ca again and replace the received certificates, keys with those that were, but when signing a new one, an error occurs.

CA certificate and CA private key do not match
139666591893152:error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch:x509_cmp.c:330:

Easy-RSA error:

signing failed (openssl output above may have more detail)