I have just enabled


I have just enabled Php 7.1 on my site and everything is working just fine except when I try to login to the backend. I get this error message :

Fatal error: Class '`' not found in /wp-defender/app/module/hardener-module/component/class-wd-prevent-php-exec.php on line 6

Can you please advise?



  • Predrag Dubajic

    Hey Karl,

    Hope you're doing well today :slight_smile:

    I have just tested Defender on my installation running PHP 7.1 but I was unable to replicate this issue.

    It could be that there was some error during Defender installation so could you access your site via FTP or cPanel and remove defender plugin from your /wp-content/plugins/ folder.
    This should allow you to access your wp-admin again so try installing the plugin again and see if it works after that.

    If the issue is still there can you please remove it again and then grant us support access so we can have a closer look at this?

    To enable support access you can follow this guide here:

    Best regards,

  • True Design

    Hi Predrag,

    I have deactivated defender and now when i try and login I get this error message :

    Warning: call_user_func_array() expects parameter 1 to be a valid callback, function '???' not found or invalid function name in /public_html/wp-includes/class-wp-hook.php on line 298

    Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 140276851299392 bytes) in /public_html/wp-includes/class-wp-hook.php on line 298

  • Adam Czajczyk

    Hello True Design,

    Thank you for your replay!

    The error means that WordPress is hitting the top limit of assigned memory and since it's already a big number (and it's trying to allocate even more) I would say that there's some issue that has yet to be tracked down. The original Defender issue may have been caused by that as well.

    While the memory limit is already set to a number high enough in most cases we now need to find out what's causing that enormous "spike" and for this a full theme/plugin conflict test is necessary. Please start with the following:

    1. access your site via FTP
    2. go to the "/wp-content/" folder
    3. rename the "plugins" folder to "plugins_off"
    4. try to login to your site

    At this point you should be able to login and when you visit the "Plugins" page you should notice that all the plugins are disabled.

    5. go to "Themes" page and switch to "Twenty Fifteen" or "Twenty Sixteen" theme

    7. access the site via FTP once again and inside the "/wp-content" folder rename "plugins_off" folder back to "plugins"

    8. on "Plugins -> All plugins" page enable a single plugin
    9. check if the site works fine
    10. repeat steps 8 and 9 until either all the necessary plugins are enabled or the site breaks

    If the site breaks, the last activated plugin would be the source of an issue.

    If all the plugins are active and the site did not break, please go to the "Themes" page and switch back to your original theme and see if it breaks now.

    That should reveal the main culprit so we could then investigate it further. Let me know about the result please.

    Best regards,

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