Title: callback, function ” not found
Last modified: October 3, 2019

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# callback, function ” not found

 *  [olaflexemo](https://wordpress.org/support/users/olaflexemo/)
 * (@olaflexemo)
 * [6 years, 6 months ago](https://wordpress.org/support/topic/callback-function-not-found/)
 * This doesn’t seem to cause problems but I was wondering if anybody can shed some
   light on what those below PHP warnings may cause?
    The first one appears when
   I click on the ‘Contacts’ link in the WP Backend and all four show up when I 
   save a form.
 * Any info is much appreciated.
 * Thanks,
    olaf
 * > [03-Oct-2019 10:11:06 UTC] PHP Warning: call_user_func_array() expects parameter
   > 1 to be a valid callback, function ” not found or invalid function name in
   > > /var/www/html/wp-includes/class-wp-hook.php on line 288
   > >  [03-Oct-2019 10:
   > > 11:06 UTC] PHP Notice: Undefined index: wpcf7pdf-use-plugins-css in /var/
   > > www/html/wp-content/plugins/wp_cf7_pdf_generator_1.3.3.zip/admin.php on line
   > > 451 [03-Oct-2019 10:11:06 UTC] PHP Notice: Undefined index: wpcf7pdf-use-
   > > of-html in /var/www/html/wp-content/plugins/wp_cf7_pdf_generator_1.3.3.zip/
   > > admin.php on line 454 [03-Oct-2019 10:11:06 UTC] PHP Warning: call_user_func_array()
   > > expects parameter 1 to be a valid callback, function ” not found or invalid
   > > function name in /var/www/html/wp-includes/class-wp-hook.php on line 288 [
   > > 03-Oct-2019 10:11:06 UTC] PHP Notice: Only variables should be passed by 
   > > reference in /var/www/html/wp-content/plugins/wp_cf7_pdf_generator_1.3.3.
   > > zip/admin.php on line 105

Viewing 1 replies (of 1 total)

 *  Plugin Author [Takayuki Miyoshi](https://wordpress.org/support/users/takayukister/)
 * (@takayukister)
 * [6 years, 6 months ago](https://wordpress.org/support/topic/callback-function-not-found/#post-11996652)
 * What other plugins and theme do you use on the site?

Viewing 1 replies (of 1 total)

The topic ‘callback, function ” not found’ is closed to new replies.

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 * 1 reply
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 * Last reply from: [Takayuki Miyoshi](https://wordpress.org/support/users/takayukister/)
 * Last activity: [6 years, 6 months ago](https://wordpress.org/support/topic/callback-function-not-found/#post-11996652)
 * Status: not resolved