I have been struggling with the missing intermediate/root chain certificates when i tried third party ssl certificate.
Check Installation
First check the installed cert. Use these tools to check your certificate
https://www.ssllabs.com/ssltest/
https://www.sslshopper.com/ssl-checker.html
To fix this problem, i would suggest
If you copy and paste the .crt use text editor make sure the cert has no extra characters.
-----BEGIN CERTIFICATE-----
-----END CERTIFICATE-----The chained certs must be according to correct order of certifying authority.
Make sure you point the ca_bundle using the apache directive for chain file.
<VirtualHost *:443>
ServerName example.com ServerAlias *.example.com DocumentRoot "/opt/bitnami/apps/wordpress/htdocs" SSLEngine on SSLCertificateFile "/opt/bitnami/apps/wordpress/conf/certs/server.crt" SSLCertificateKeyFile "/opt/bitnami/apps/wordpress/conf/certs/server.key" SSLCertificateChainFile "/opt/bitnami/apps/wordpress/conf/certs/server-ca.crt"
</VirtualHost>
Missing chain or intermediary error.
If you use latest bitnami with apache2 with latest bitnami, you might want to SSLCACertificateFile use follow to this guide
SSLCACertificateFile "/opt/bitnami/wordpress/keys/cabundle.crt"