How to block Bugsnag script fetcher
Operated by Bugsnag. Bugsnag script fetcher is a bot operated by Bugsnag, an error monitoring and reporting platform for software applications. This bot fetches JavaScript source files and source maps from websites to help developers debug errors by providing readable stack traces.
nginx
In the server block, then reload.
# In the server block. 403 rather than 444: a closed connection tells the
# operator nothing, and an agent that gets a status code can log it.
if ($http_user_agent ~* "(Bugsnag script fetcher)") {
return 403;
}
Apache
In .htaccess or the vhost.
BrowserMatchNoCase "Bugsnag script fetcher" bad_bot
<RequireAll>
Require all granted
Require not env bad_bot
</RequireAll>
Cloudflare
Security → WAF → Custom rules.
# Security → WAF → Custom rules, action: Block (http.user_agent contains "Bugsnag script fetcher")
WordPress
A child theme's functions.php, or a small plugin.
// functions.php of a child theme, or a small plugin. Runs before WordPress
// builds the page, so a blocked agent costs one PHP process and no queries.
add_action('init', function () {
$agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
foreach (['Bugsnag script fetcher'] as $needle) {
if (stripos($agent, $needle) !== false) {
status_header(403);
exit('Blocked: Bugsnag script fetcher');
}
}
});
A rule on the user agent is a rule on a string it chose
The server rules match on a header the requester sets, which stops the agent that says who it is and not the one that copies somebody else's name. Botscope verifies identity against DNS and published address ranges, records which check decided each request, and shows you the ones that lied.