Pages don't show; WP reports error

My pages don't show anymore.
WordPress reports an error in the theme:

Foutdetails
===========
Een fout van het type E_ERROR werd veroorzaakt op regelnummer 908 van het bestand ///wp-content/themes/themiatheme/functions/admin-interface.php. Foutmelding: Uncaught Error: Call to undefined function ereg_replace() in ///wp-content/themes/themiatheme/functions/admin-interface.php:908
Stack trace:
#0 //wp-content/themes/themiatheme/functions/admin-interface.php(114): optionsframework_machine(Array)
#1 //wp-includes/class-wp-hook.php(286): optionsframework_options_page('')
#2 //wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters('', Array)
#3 //wp-includes/plugin.php(465): WP_Hook->do_action(Array)
#4 //wp-admin/admin.php(253): do_action('appearance_page...')
#5 //wp-admin/themes.php(10): require_once('/var/www/client...')
#6 {main}
thrown

I have removed the path information from the error text.
Site: riethaschuur.nl
WP version: 5.2.3
Themia Pro 2.2.1

 

Solved it!
For some obscure reason the custom permalink to the pages was incorrect (which is strange, because why change it on a working site).
Anyway, after restoring the intended permalink, the pages reappeared.
Sorry to have bothered you.
Milly