# Buggy code
def add_parser_arguments(cls, add):
    add(
        "enmod",
        default=constants.os_constant("enmod"),
        help="Path to the Apache 'a2enmod' binary.",
    )
    add(
        "dismod",
        default=constants.os_constant("dismod"),
        help="Path to the Apache 'a2dismod' binary.",
    )
    add(
        "le-vhost-ext",
        default=constants.os_constant("le_vhost_ext"),
        help="SSL vhost configuration extension.",
    )
    add(
        "server-root",
        default=constants.os_constant("server_root"),
        help="Apache server root directory.",
    )
    add(
        "vhost-root",
        default=constants.os_constant("vhost_root"),
        help="Apache server VirtualHost configuration root",
    )
    add(
        "logs-root",
        default=constants.os_constant("logs_root"),
        help="Apache server logs directory",
    )
    add(
        "challenge-location",
        default=constants.os_constant("challenge_location"),
        help="Directory path for challenge configuration.",
    )
    add(
        "handle-modules",
        default=constants.os_constant("handle_mods"),
        help="Let installer handle enabling required modules for you."
        + "(Only Ubuntu/Debian currently)",
    )
    add(
        "handle-sites",
        default=constants.os_constant("handle_sites"),
        help="Let installer handle enabling sites for you."
        + "(Only Ubuntu/Debian currently)",
    )
    util.add_deprecated_argument(add, argument_name="ctl", nargs=1)
    util.add_deprecated_argument(add, argument_name="init-script", nargs=1)


# Traceback (PluginError)
Cannot find a cert or key directive in /files/etc/apache2/sites-available/default-ssl.conf/IfModule/VirtualHost. VirtualHost was not modified
Encountered exception:
Traceback (most recent call last):
File "/home/bmw/src/certbot/certbot/client.py", line 439, in deploy_certificate
fullchain_path=fullchain_path)
File "/home/bmw/src/certbot/certbot-apache/certbot_apache/configurator.py", line 269, in deploy_cert
"Unable to find cert and/or key directives")
PluginError: Unable to find cert and/or key directives

Calling registered functions
Reporting to user: Unable to install the certificate
Exiting abnormally:
Traceback (most recent call last):
File "/usr/local/bin/certbot", line 11, in <module>
load_entry_point('certbot', 'console_scripts', 'certbot')()
File "/home/bmw/src/certbot/certbot/main.py", line 743, in main
return config.func(config, plugins)
File "/home/bmw/src/certbot/certbot/main.py", line 604, in run
_install_cert(config, le_client, domains, new_lineage)
File "/home/bmw/src/certbot/certbot/main.py", line 469, in _install_cert
path_provider.cert_path, path_provider.chain_path, path_provider.fullchain_path)
File "/home/bmw/src/certbot/certbot/client.py", line 439, in deploy_certificate
fullchain_path=fullchain_path)
File "/home/bmw/src/certbot/certbot-apache/certbot_apache/configurator.py", line 269, in deploy_cert
"Unable to find cert and/or key directives")
PluginError: Unable to find cert and/or key directives

# Fixed code
def add_parser_arguments(cls, add):
    add(
        "enmod",
        default=constants.os_constant("enmod"),
        help="Path to the Apache 'a2enmod' binary.",
    )
    add(
        "dismod",
        default=constants.os_constant("dismod"),
        help="Path to the Apache 'a2dismod' binary.",
    )
    add(
        "le-vhost-ext",
        default=constants.os_constant("le_vhost_ext"),
        help="SSL vhost configuration extension.",
    )
    add(
        "server-root",
        default=constants.os_constant("server_root"),
        help="Apache server root directory.",
    )
    add("vhost-root", default=None, help="Apache server VirtualHost configuration root")
    add(
        "logs-root",
        default=constants.os_constant("logs_root"),
        help="Apache server logs directory",
    )
    add(
        "challenge-location",
        default=constants.os_constant("challenge_location"),
        help="Directory path for challenge configuration.",
    )
    add(
        "handle-modules",
        default=constants.os_constant("handle_mods"),
        help="Let installer handle enabling required modules for you."
        + "(Only Ubuntu/Debian currently)",
    )
    add(
        "handle-sites",
        default=constants.os_constant("handle_sites"),
        help="Let installer handle enabling sites for you."
        + "(Only Ubuntu/Debian currently)",
    )
    util.add_deprecated_argument(add, argument_name="ctl", nargs=1)
    util.add_deprecated_argument(add, argument_name="init-script", nargs=1)