Title: Undefined function mb_strpos
Last modified: October 27, 2023

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# Undefined function mb_strpos

 *  [WP User](https://wordpress.org/support/users/mtfalk/)
 * (@mtfalk)
 * [2 years, 7 months ago](https://wordpress.org/support/topic/undefined-function-mb_strpos/)
 * As soon as I enable this extension on my site, I get the following error about
   mb_strpos being undefined:
 * > Fatal error: Uncaught Error: Call to undefined function Woo_Store_Vacation\
   > Settings\Sections\mb_strpos() in /public_html/wp-content/plugins/woo-store-
   > vacation/src/Settings/Sections/Section.php:42
   > Stack trace: #0 [internal function]: Woo_Store_Vacation\Settings\Sections\Section::
   > Woo_Store_Vacation\Settings\Sections{closure}(‘section_title’) 1 /public_html/
   > wp-content/plugins/woo-store-vacation/src/Settings/Sections/Section.php(43):
   > array_filter(Array, Object(Closure)) 2 /public_html/wp-content/plugins/woo-
   > store-vacation/src/Settings/Sections/Conditions.php(101): Woo_Store_Vacation\
   > Settings\Sections\Section->get_field_keys() 3 /public_html/wp-content/plugins/
   > woo-store-vacation/src/WooCommerce/Vacation.php(95): Woo_Store_Vacation\Settings\
   > Sections\Conditions->get_active() 4 /public_html/wp-includes/class-wp-hook.
   > php(310): Woo_Sto in /public_html/wp-content/plugins/woo-store-vacation/src/
   > Settings/Sections/Section.php on line 42
 * According to the answers on [this StackOverflow question](https://stackoverflow.com/questions/9692157/php-missing-mb-strpos-function),
   mbstring is a nonstandard/nondefault library in PHP, and PHP needs to be custom-
   built to support it.
 * We’ve never had a problem with missing PHP functionality with any other extensions
   or any of our own site code. Shouldn’t this WooCommerce Store Vacation extension
   work with basic PHP methods and not require custom/special PHP functionality?
    -  This topic was modified 2 years, 7 months ago by [WP User](https://wordpress.org/support/users/mtfalk/).

The topic ‘Undefined function mb_strpos’ is closed to new replies.

 * ![](https://ps.w.org/woo-store-vacation/assets/icon-256x256.gif?rev=2923942)
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 * 0 replies
 * 1 participant
 * Last reply from: [WP User](https://wordpress.org/support/users/mtfalk/)
 * Last activity: [2 years, 7 months ago](https://wordpress.org/support/topic/undefined-function-mb_strpos/)
 * Status: not resolved