Uncaught Error: Call to undefined function

Hello,

The website breaks whenever we update or publish a new event, i.e. a critical error is received and we need to to log in with recovery mode, before being able to activate the plugin again, before trying again (when the same issue reoccurs) – see below:
An error of type E_ERROR was caused in line 72 of the file /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/mep_functions.php. Error message: Uncaught Error: Call to undefined function mb_regex_encoding() in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/mep_functions.php:72 Stack trace: #0 /home//public_html/shop/wp-content/plugins/mage-eventpress/Admin/settings/MPWEM_Settings.php(81): mep_letters_numbers_spaces_only(‘Head o…’) #1 /home//public_html/shop/wp-includes/class-wp-hook.php(326): MPWEM_Settings->save_settings(104569) #2 /home//public_html/shop/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(false, Array) #3 /home//public_html/shop/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #4 /home//public_html/shop/wp-includes/post.php(5110): do_action(‘save_post’, 104569, Object(WP_Post), true) #5 /home//public_html/shop/wp-includes/post.php(5212): wp_insert_post(Array, false, true) #6 /home//public_html/shop/wp-admin/includes/post.php(453): wp_update_post(Array) #7 /home//public_html/shop/wp-admin/post.php(227): edit_post() #8 {main} thrown

Kindly see the error log entries below – we have updated the plugin, theme and WordPress, disabled all other plugins and activated a default theme, etc:
[05-Aug-2025 12:21:06 UTC] PHP Warning: Undefined array key “mep_street” in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 219
[05-Aug-2025 12:21:06 UTC] PHP Warning: Trying to access array offset on value of type null in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 219
[05-Aug-2025 12:21:06 UTC] PHP Warning: Undefined array key “mep_city” in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 235
[05-Aug-2025 12:21:06 UTC] PHP Warning: Trying to access array offset on value of type null in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 235
[05-Aug-2025 12:21:06 UTC] PHP Warning: Undefined array key “mep_state” in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 251
[05-Aug-2025 12:21:06 UTC] PHP Warning: Trying to access array offset on value of type null in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 251
[05-Aug-2025 12:21:06 UTC] PHP Warning: Undefined array key “mep_country” in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 283
[05-Aug-2025 12:21:06 UTC] PHP Warning: Trying to access array offset on value of type null in /home//public_html/shop/wp-content/plugins/mage-eventpress/inc/template-prts/event_location.php on line 283

Thank you in advance for your feedback.

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