The Http::sendHttpRequest() function already handles http errors and returns false. So there needs to be some other problem. Maybe squid does not correctly answer with http status 403?

To prevent this issue on Matomo site, a new function should be added to core/Http.php like this:

public static function sendHttpRequestWithExpectedResult($aUrl,
                                           $expectedPattern,
                                           $timeout,
                                           $userAgent = null,
                                           $destinationPath = null,
                                           $followDepth = 0,
                                           $acceptLanguage = false,
                                           $byteRange = false,
                                           $getExtendedInfo = false,
                                           $httpMethod = 'GET', 
                                           $httpUsername = null,
                                           $httpPassword = null)
    {
        // Do the same as in sendHttpRequest but do a preg_match() against the body afterwards.
    }

If you like this solution I'll provide a PR for that.

Any opinions?

Maybe we could add a system check for it? To test we receive a version number?

@tsteur That won't help people who have a proxy blocking the request without their knowledge.

Sorry not sure I get it. I read the forum post... as we probably don't really want to fail during run time when that request fails, it may be better to show it in a system check (which is also shown on Admin Home) that something is wrong / not working?

Ah, sorry my mistake. A system check is a great idea. (I read system test, which wouldn't make any sense)

👍

That check should also allow to see the returned error message if there is one.