Title: Multisite Last modified: September 16, 2026 --- # Multisite * Resolved [Quique5](https://wordpress.org/support/users/quique5/) * (@quique5) * [2 weeks, 1 day ago](https://wordpress.org/support/topic/multisite-755/) * Hi everyone, * I opened this ticket some time ago: [https://wordpress.org/support/topic/plugins-problem-in-multisite-installation/](https://wordpress.org/support/topic/plugins-problem-in-multisite-installation/) * The problem was never resolved, and I am still running version 6.14.2 because I cannot upgrade to any newer version. * I keep getting the following error: * ```wp-block-code [16-Sep-2026 07:23:00 UTC] PHP Fatal error: Cannot redeclare check_upload_size() (previously declared in /home/www/multisite/htdocs/wp-admin/includes/ms.php:18) in /home/www/multisite/htdocs/wp-admin/includes/ms.php on line 18 [16-Sep-2026 07:23:26 UTC] PHP Fatal error: Cannot redeclare check_upload_size() (previously declared in /home/www/multisite/htdocs/wp-admin/includes/ms.php:18) in /home/www/multisite/htdocs/wp-admin/includes/ms.php on line 18 ``` * With other plugins, I have been able to work around similar issues by commenting out a line such as this one: * ```wp-block-code // Load WP user management functions if ( is_multisite() ) { // require_once( ABSPATH . 'wp-admin/includes/ms.php' ); <---- this one! } ``` * However, in this case I cannot find any reference to anything similar. * I am particularly concerned because of the latest security vulnerability reported by Wordfence, as I am unable to update to a newer version. * Does anyone have any idea what could be causing this `Cannot redeclare check_upload_size()` error or how I could fix it so that I can update? * The error occurs when logging in. If I do not log in, there are no errors and the website looks fine. However, as soon as I enter a username and password and log in, the **FATAL ERROR** appears. * Thanks in advance for any help. - This topic was modified 2 weeks, 1 day ago by [Quique5](https://wordpress.org/support/users/quique5/). Viewing 10 replies - 1 through 10 (of 10 total) * Thread Starter [Quique5](https://wordpress.org/support/users/quique5/) * (@quique5) * [2 weeks, 1 day ago](https://wordpress.org/support/topic/multisite-755/#post-19021357) * important: The error occurs when logging in. If I do not log in, there are no errors and the website looks fine. However, as soon as I enter a username and password and log in, the **FATAL ERROR** appears. * Plugin Support [Darian](https://wordpress.org/support/users/d0153/) * (@d0153) * [2 weeks, 1 day ago](https://wordpress.org/support/topic/multisite-755/#post-19021601) * Hi [@quique5](https://wordpress.org/support/users/quique5/), * Thanks for reaching out. I’ll be happy to assist you with this. * I investigated the issue further, but unfortunately, I wasn’t able to reproduce it on my end. Could you please try adding the following snippet to see whether it resolves the issue? * ```wp-block-code add_filter( 'shepherd_tec_should_log', '__return_false' ); ``` * You can add it using the Code Snippets plugin. As always, please test this first on a staging site before applying it to your live site. * Please let me know how it goes. * Thread Starter [Quique5](https://wordpress.org/support/users/quique5/) * (@quique5) * [2 weeks, 1 day ago](https://wordpress.org/support/topic/multisite-755/#post-19021662) * I tried but it failed again I am using: Divi plugin, AuthLDAP and WPS Hide Login. * This is the content in debug.log: * ```wp-block-code [16-Sep-2026 14:06:29 UTC] PHP Warning: require_once(/home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/action-scheduler.php): failed to open stream: No such file or directory in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Tribe/Main.php on line 527[16-Sep-2026 14:06:29 UTC] PHP Fatal error: require_once(): Failed opening required '/home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/action-scheduler.php' (include_path='.:/opt/remi/php74/root/usr/share/pear:/opt/remi/php74/root/usr/share/php:/usr/share/pear:/usr/share/php') in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Tribe/Main.php on line 527[16-Sep-2026 14:06:29 UTC] PHP Warning: require_once(/home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/action-scheduler.php): failed to open stream: No such file or directory in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Tribe/Main.php on line 527[16-Sep-2026 14:06:29 UTC] PHP Fatal error: require_once(): Failed opening required '/home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/action-scheduler.php' (include_path='.:/opt/remi/php74/root/usr/share/pear:/opt/remi/php74/root/usr/share/php:/usr/share/pear:/usr/share/php') in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Tribe/Main.php on line 527[16-Sep-2026 14:06:32 UTC] PHP Warning: require_once(/home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/classes/ActionScheduler_Versions.php): failed to open stream: No such file or directory in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/action-scheduler.php on line 35[16-Sep-2026 14:06:32 UTC] PHP Fatal error: require_once(): Failed opening required '/home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/classes/ActionScheduler_Versions.php' (include_path='.:/opt/remi/php74/root/usr/share/pear:/opt/remi/php74/root/usr/share/php:/usr/share/pear:/usr/share/php') in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/woocommerce/action-scheduler/action-scheduler.php on line 35[16-Sep-2026 14:06:43 UTC] PHP Fatal error: Uncaught TEC\Common\Exceptions\Not_Bound_Exception: Error while making TEC\Events\Integrations\Plugins\WordPress_SEO\Provider: nothing is bound to the 'TEC\Events\Integrations\Plugins\WordPress_SEO\Provider' id and it's not an existing or instantiable class. in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Common/Contracts/Container.php:35Stack trace: 0 /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/vendor-prefixed/lucatume/di52/src/Container.php(457): TEC\Common\Contracts\Container->get() 1 /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Common/Contracts/Container.php(63): TEC\Common\lucatume\DI52\Container->register() 2 /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/src/Events/Integrations/Provider.php(32): TEC\Common\Contracts\Container->register() 3 /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/vendor-prefixed/lucatume/di52/src/Container.php(459): TEC\Event in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Common/Contracts/Container.php on line 35[16-Sep-2026 14:06:50 UTC] PHP Fatal error: Uncaught Error: Interface 'Tribe\Events\Views\V2\View_Interface' not found in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/src/Tribe/Views/V2/View.php:43Stack trace: 0 /home/www/multisite/htdocs/wp-content/plugins/code-snippets/vendor/composer/ClassLoader.php(576): include() 1 /home/www/multisite/htdocs/wp-content/plugins/code-snippets/vendor/composer/ClassLoader.php(427): Composer\Autoload{closure}() 2 [internal function]: Composer\Autoload\ClassLoader->loadClass() 3 /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/src/Tribe/Views/V2/Service_Provider.php(63): spl_autoload_call() 4 /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/vendor/vendor-prefixed/lucatume/di52/src/Container.php(459): Tribe\Events\Views\V2\Service_Provider->register() 5 /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/common/src/Common/Contracts/Container.php(63): TEC\Common\lucatume\DI52\Container->register() 6 /home/www/multisite/htdocs/wp-content/p in /home/www/multisite/htdocs/wp-content/plugins/the-events-calendar/src/Tribe/Views/V2/View.php on line 43 ``` * Plugin Support [Darian](https://wordpress.org/support/users/d0153/) * (@d0153) * [2 weeks ago](https://wordpress.org/support/topic/multisite-755/#post-19022506) * Hi [@quique5](https://wordpress.org/support/users/quique5/) , * Thanks for sending the log. These errors are different from the original one. They show that The Events Calendar’s folder contains files from two versions at once (6.14.2 and a newer one). This usually happens when an update gets interrupted, or when a new version is uploaded on top of the old folder. * To clean this up, could you try the following? 1. **Take a full backup** of your site’s files and database. 2. **Replace the plugin folder.** Using FTP or your host’s file manager, delete the `the-events-calendar` folder from `wp-content/plugins/` (or move it outside that directory). Then upload a fresh copy of version 6.17.4.1. Please don’t upload it over the existing folder, since that can leave old files behind. Your events and settings are stored in the database, so they won’t be lost. If the plugin shows as deactivated afterward, network-activate it again. 3. **Restart PHP-FPM**, or ask your host to do it. This clears any old code still cached in memory. 4. **Add the previous snippet that I provided to a fix file (e.g. shepherd_fix. php)** **to `wp-content/mu-plugins/`.** If that folder doesn’t exist, you can create it. The file won’t work as a Code Snippet because snippets load too late to apply the fix. 5. **Log in and test.** If it still fails, please send the new `debug.log` entries from after these steps. * Let me know how it goes. * Thread Starter [Quique5](https://wordpress.org/support/users/quique5/) * (@quique5) * [1 week, 6 days ago](https://wordpress.org/support/topic/multisite-755/#post-19023281) * same behavior, this is the error * > add_filter( ‘shepherd_tec_should_log’, ‘__return_false’ ); > Fatal error: Cannot > redeclare check_upload_size() (previously declared in /home/www/multisite/htdocs/ > wp-admin/includes/ms.php:18) in /home/www/multisite/htdocs/wp-admin/includes/ > ms.php on line 18Ha habido un error crítico en esta web. > Aprende más sobre el diagnóstico de WordPress. * and same in debug.log: * ```wp-block-code [18-Sep-2026 10:28:06 UTC] PHP Fatal error: Cannot redeclare check_upload_size() (previously declared in /home/www/multisite/htdocs/wp-admin/includes/ms.php:18) in /home/www/multisite/htdocs/wp-admin/includes/ms.php on line 18[18-Sep-2026 10:28:43 UTC] PHP Fatal error: Cannot redeclare check_upload_size() (previously declared in /home/www/multisite/htdocs/wp-admin/includes/ms.php:18) in /home/www/multisite/htdocs/wp-admin/includes/ms.php on line 18 ``` * Plugin Support [Darian](https://wordpress.org/support/users/d0153/) * (@d0153) * [1 week, 6 days ago](https://wordpress.org/support/topic/multisite-755/#post-19023561) * Hi [@quique5](https://wordpress.org/support/users/quique5/), * Thanks for your response. * It looks like the snippet isn’t taking effect, most likely because it runs too late in the load process or it was implemented incorrectly. Let’s try it as a must-use plugin instead, which loads before everything else. 1. Remove the snippet you added earlier. 2. Using FTP or your host’s file manager, create this file: `wp-content/mu-plugins/ tec-shepherd-no-early-admin-includes.php`If the `mu-plugins` folder doesn’t exist yet, you can create it. 3. Add the following to the file and save it: * ```wp-block-code