I’ve just released version 1.1.0 of JSM’s Block Filter Output – a new plugin to monitor the content filter and fix incorrectly coded filter hooks (that send text to the webpage instead of returning it, as all filter hooks must).
A notice is also sent to the PHP error log when webpage output is detected:
[01-Oct-2017 01:48:28 UTC] Block Filter Output: The “ClassName::echoText” filter hook with priority 10 in the “the_content” filter has mistakenly provided some webpage output. All WordPress filter hooks must return their text – not send it to the webpage output. Please contact the author of that filter hook and report this issue as a coding error / bug. Incorrect webpage output:
<strong>Some output that should have been returned instead of echo’ed.</strong>
The plugin is fully tested and compatible with PHP v7.x (PHP v5.3 or better required).
Power-users / Developers
If you haven’t enabled the WP_DEBUG constant yet, you should set the WP_DEBUG constant to true in your wp-config.php file to find out about these and any other PHP / WordPress coding errors. 😉
The plugin only monitors the “the_content” filter by default. You can customize the list of monitored filters by defining the JSM_BFO_FILTER_NAMES constant.
define( 'JSM_BFO_FILTER_NAMES', array(
You can also monitor the special WordPress “all” filter, although this is not recommended as it this may have a negative effect on you site’s performance:
define( 'JSM_BFO_FILTER_NAMES', 'all' );
Plugins Using the BFO Library
The WPSSO Core plugin uses the BFO library when the “Use WordPress Content Filters” option is enabled in its Advanced settings page.