Why your PHP snippet isn't running

A PHP snippet that does nothing is almost always one of 9 things. Work through this list from the top; the first 3 catch most cases.

1. The snippet isn't published

Open Components → Tassos Code Snippets and check the Status column. Auto-Disabled means the snippet failed and Code Snippets switched it off: open it, read the error at the top of the edit screen, fix the code and publish it again. How to debug PHP errors in a snippet covers the common errors.

2. The Location doesn't match where you're looking

The Location of a PHP snippet picks the client it runs in:

• Site Page Load runs on the frontend only.
• Admin Page Load runs in the administrator only.
• Site and Admin Page Load runs in both.

A snippet on Site Page Load never runs while you click around the administrator, and the other way round. The 2 admin locations are part of Code Snippets Pro.

3. A condition or the access level hides it

Open the Conditional Logic tab and check every rule. A condition that doesn't match the current page skips the snippet without any error. Then check Access in the sidebar: Code Snippets only loads the snippets the current visitor is allowed to view. A snippet that must react to a login, on the site or in the administrator, has to stay Public, because the login request comes from a guest.

4. The system plugin is disabled

Go to System → Plugins and search for Tassos Code Snippets. The System - Tassos Code Snippets plugin is what runs the snippets. With it disabled, the component still saves them but none of them execute.

5. Safe mode is on

If someone added tcs_safe_mode to configuration.php to recover from a broken snippet, every snippet is paused until that line goes. The component's pages show a warning while it's on. See Use safe mode to recover from a snippet that locks you out.

6. The output goes nowhere useful

Page Load snippets run during onAfterRoute, before Joomla has built the page. Anything they echo is printed before the page's HTML, where it breaks the markup instead of showing a message. To show something, queue a message:

use Joomla\CMS\Factory;

Factory::getApplication()->enqueueMessage('The snippet ran', 'notice');

Output only matters for the Shortcode insertion method, where what the snippet echoes or returns replaces the shortcode. Shortcodes are replaced on the frontend only.

7. The code runs too early

At onAfterRoute the document isn't built yet and the article text isn't loaded, so code that touches the page has nothing to work with. Wrap it in a later event, as the Example section of the PHP snippet docs shows: onBeforeCompileHead for the page head, onAfterRender for the final output, onContentPrepare for article text.

8. The code uses a blocked function

Snippets that contain exec, eval, fopen and a few other functions never execute. The full list is in the PHP snippet docs under Security Considerations.

9. A cached page is served

With System - Page Cache enabled, visitors may get a stored copy of the page, so a snippet that changes the output seems to do nothing. Clear the cache under System → Clear Cache and reload.

Still stuck? Put the enqueueMessage line from point 6 at the top of the snippet. If the message appears, the snippet runs and the problem is in the code below it. If it doesn't, one of the first 5 points is the cause.