I saw the follow:

The following error just broke Matomo (v4.9.1):

Call to undefined function Piwik\Plugins\RssWidget\simplexml_load_string()
in /srv/matomo/plugins/RssWidget/RssRenderer.php line 62      

when visiting /index.php?date=yesterday&module=RssWidget&action=rssPiwik&disableLink=0&widget=1&idSite=8590&period=day

Expected Behavior

Going to /index.php?date=yesterday&module=RssWidget&action=rssPiwik&disableLink=0&widget=1&idSite=8590&period=day is not expected to throw an error.

Current Behavior

An error is thrown when going to /index.php?date=yesterday&module=RssWidget&action=rssPiwik&disableLink=0&widget=1&idSite=8590&period=day.

Possible Solution

Maybe it should be like:

                $rss = @\simplexml_load_string($content);
                if ($rss === false) {
                    throw new \Exception("Failed to parse XML.");
                }

?

Steps to Reproduce (for Bugs)

1. Go to /index.php?date=yesterday&module=RssWidget&action=rssPiwik&disableLink=0&widget=1&idSite=8590&period=day

Context

Your Environment

• Matomo Version: 4.9.1
• PHP Version: 7.4.28
• Server Operating System: debian 11
• Additionally installed plugins:

• Browser: Safari (v15.4 (17613.1.17.1.13))
• Operating System: Mac OS 12.3.1