The error and next steps are pretty well outlined in the messages you recieved
MisconfigurationError: Error while running apache2ctl graceful.
httpd not running, trying to start
Action 'graceful' failed.
The Apache error log may have more information.
Error while running apache2ctl graceful.
httpd not running, trying to start
Action 'graceful' failed.
The Apache error log may have more information.
AH00112: Warning: DocumentRoot [/var/lib/letsencrypt/tls_sni_01_page/] does not exist