Fatal when other plugins use old-style constructors

[simonwheatley]

If a plugin uses the old-style constructor then Query Monitor fails with a PHP fatal error on WPEngine:

Fatal error: Class 'QM_Util' not found in /nas/wp/www/staging/pencil/wp-content/plugins/co-authors-plus/co-authors-plus.php on line 112

If the old style constructor method is commented out, leaving the proper __construct, then the fatal goes away.

[simonwheatley]

I cannot work out what in QM is getting run on these constructors so I can determine a fix. Do you know what might be getting triggered on an old-style constructor?

[simonwheatley]

I've tracked it down to the QM_Component_PHP_Errors class calling QM_Util::backtrace() before it's available. Requiring the file if the method isn't callable does not seem to help. Quick fix was to change the method as follows:

diff --git a/wp-content/plugins/query-monitor/components/php_errors.php b/wp-content/plugins/query-monitor/components/php_errors.php
index 3a95363..0f84c48 100755
--- a/wp-content/plugins/query-monitor/components/php_errors.php
+++ b/wp-content/plugins/query-monitor/components/php_errors.php
@@ -173,6 +173,19 @@ class QM_Component_PHP_Errors extends QM_Component {

        if ( error_reporting() > 0 ) {

+           if ( ! is_callable( 'QM_Util::backtrace' ) ) {
+               $this->data['errors'][$type][$key] = (object) array(
+                   'errno'    => $errno,
+                   'type'     => $type,
+                   'message'  => $message,
+                   'file'     => $file,
+                   'filename' => 'unknown',
+                   'line'     => $line,
+                   'funcs'    => 'unknown',
+                   'calls'    => 1
+               );
+               return;
+           }
            $funcs = QM_Util::backtrace();

            if ( !isset( $funcs[0] ) )

[johnbillion]

Can you try updating to the latest QM code from the GitHub repo? It should fix that issue.

[simonwheatley]

Updating didn't seem to fix it. QM on WPE is v2.4.1.

[simonwheatley]

(Double checking that.)

[johnbillion]

Ah ok, I just looked in the cftp/ir-2013 repo and saw QM was still on a 2.4 beta.

[simonwheatley]

I hadn't pushed the IR changes to GitHub. Here they are now:

• https://github.com/cftp/ir-2013/commit/43387ebeb0197055d02af72b24dea744361a9718#L6R5
• https://github.com/cftp/ir-2013/commit/cabad94e7d7b34fa00a65790a5a25d0837372155

Anyway, this is getting dangerously close to you doing Work™. I'm going to shut up now.

[johnbillion]

^ Internet Retailing site on WPE.

/me gone.

[simonwheatley]

whispers I'm testing on staging. ;)

/me was never here

[scottsweb]

Seeing this issue too when activating plugins on Pearson (WPE again).

Fatal error: Class 'QM_Util' not found in /nas/wp/www/cluster-1678/pearson/wp-content/plugins/video-library/Plugin.php on line 78

I am running 2.4.1 of QM and this is against our own Video Library plugin.

[simonwheatley]

@scottsweb – If you patch QM with this https://github.com/cftp/st-jpp/commit/cabad94e7d7b34fa00a65790a5a25d0837372155 does it work for you?

[johnbillion]

I think this is a combination of the way strict errors are reported on WPE and the fact that WPE doesn't allow the wp-content/db.php symlink to be put into place. I'll take a look at my next available opportunity :)

[scottsweb]

Before even applying the patch @simonwheatley I decided to deactivate and reactivate the plugin... and it worked. So without the patch a second activation seems fine.

I have now applied the patch and will see if it appears again.