How to fix AH02565: Certificate and private key do not match

We have an application hosted on Ubuntu apache server and letsencrypt SSL is installed there. Now i want to change Letsencrypt ssl certificate by Digicert certificate. I followed the Digicert ssl installation document and when i try to start my apache server its gonna failed. After check error log i found below error.

AH02565: Certificate and private key urbaninspirations.biz:443:0 from /etc/cert/domain_name.crt and /etc/cert/domain_name.key do not match
AH00016: Configuration Failed

Below is my "000-default-le-ssl.conf" page script

<VirtualHost *:443>
    ServerName domain_name.biz
    ServerAlias www.domain_name.biz
    SSLEngine On
    ServerAdmin webmaster@localhost
    DocumentRoot /var/www/html
    
    ### This is using in Letsencrypt SSL certificates
    Include /etc/letsencrypt/options-ssl-apache.conf
    SSLCertificateFile /etc/letsencrypt/live/domain_name.biz/fullchain.pem
    SSLCertificateKeyFile /etc/letsencrypt/live/domain_name.biz/privkey.pem

    ### Change this for DigiCert SSL certification but getting error when enable below line
    #SSLCertificateFile /etc/cert/domain_name.crt
    #SSLCertificateKeyFile /etc/cert/domain_name.key
    #SSLCertificateChainFile /etc/cert/DigiCertCA.crt
</VirtualHost>

Can anybody point me in the right direction for what i'm doing wrong?

The private key must match with the certificate('s public key) you use. Otherwise you won't be able to use them together.

One way to make sure both key and certificate match (certificate comes from the private key being used) is by checking their modulus with openssl.

openssl rsa -in file.key -noout -modulus

openssl x509 -in file.crt -noout -modulus

Note: If certificate or key are not in ASCII you must add "-inform DER" to the specific file.

The output of both commands must be the same.