Fatal error: Uncaught TypeError: WP_Translation_Controller::set_locale(): Argument #1 ($locale) must be of type string, null given, called in /srv/www/wordpress/wp-includes/l10n.php on line 804 and defined in /srv/www/wordpress/wp-includes/l10n/class-wp-translation-controller.php:87 Stack trace: #0 /srv/www/wordpress/wp-includes/l10n.php(804): WP_Translation_Controller->set_locale() #1 /srv/www/wordpress/wp-includes/l10n.php(960): load_textdomain() #2 /srv/www/wordpress/wp-content/plugins/polylang/include/olt-manager.php(75): load_default_textdomain() #3 /srv/www/wordpress/wp-includes/class-wp-hook.php(343): PLL_OLT_Manager->load_textdomains() #4 /srv/www/wordpress/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters() #5 /srv/www/wordpress/wp-includes/plugin.php(522): WP_Hook->do_action() #6 /srv/www/wordpress/wp-content/plugins/polylang/frontend/choose-lang.php(112): do_action() #7 /srv/www/wordpress/wp-content/plugins/polylang/frontend/choose-lang-url.php(82): PLL_Choose_Lang->set_language() #8 /srv/www/wordpress/wp-content/plugins/polylang/frontend/choose-lang-url.php(34): PLL_Choose_Lang_Url->set_language_from_url() #9 /srv/www/wordpress/wp-content/plugins/polylang/frontend/frontend.php(131): PLL_Choose_Lang_Url->init() #10 /srv/www/wordpress/wp-content/plugins/polylang/include/class-polylang.php(291): PLL_Frontend->init() #11 /srv/www/wordpress/wp-content/plugins/polylang/include/class-polylang.php(234): Polylang->init_context() #12 /srv/www/wordpress/wp-includes/class-wp-hook.php(341): Polylang->init() #13 /srv/www/wordpress/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters() #14 /srv/www/wordpress/wp-includes/plugin.php(522): WP_Hook->do_action() #15 /srv/www/wordpress/wp-settings.php(593): do_action() #16 /srv/www/wordpress/wp-config.php(96): require_once('...') #17 /srv/www/wordpress/wp-load.php(50): require_once('...') #18 /srv/www/wordpress/wp-blog-header.php(13): require_once('...') #19 /srv/www/wordpress/index.php(17): require('...') #20 {main} thrown in /srv/www/wordpress/wp-includes/l10n/class-wp-translation-controller.php on line 87

Fatal error: Uncaught TypeError: WP_Translation_Controller::set_locale(): Argument #1 ($locale) must be of type string, null given, called in /srv/www/wordpress/wp-includes/l10n.php on line 804 and defined in /srv/www/wordpress/wp-includes/l10n/class-wp-translation-controller.php:87 Stack trace: #0 /srv/www/wordpress/wp-includes/l10n.php(804): WP_Translation_Controller->set_locale() #1 /srv/www/wordpress/wp-includes/l10n.php(960): load_textdomain() #2 /srv/www/wordpress/wp-includes/class-wp-fatal-error-handler.php(49): load_default_textdomain() #3 [internal function]: WP_Fatal_Error_Handler->handle() #4 {main} thrown in /srv/www/wordpress/wp-includes/l10n/class-wp-translation-controller.php on line 87