"Could not find valid value for id" after event registration on WordPress 5.9.1 and CiviCRM 5.47.2

Question

When participants confirm the registration to an event (paid, in this case, but the error is the same for free ones), an error appears (the one in the title). The bug stack in the logs:

CRM_Core_Exception: Could not find valid value for id in /var/www/wordpress/wp-content/plugins/civicrm/civicrm/CRM/Event/StateMachine/Registration.php on line 27

0   CRM_Utils_Request::retrieve('id', 'Positive', Object(CRM_Event_Controller_Registration), true)  /var/www/wordpress/wp-content/plugins/civicrm/civicrm/CRM/Event/StateMachine/Registration.php:27
1   CRM_Event_StateMachine_Registration->__construct(Object(CRM_Event_Controller_Registration), true)   /var/www/wordpress/wp-content/plugins/civicrm/civicrm/CRM/Event/Controller/Registration.php:27
2   CRM_Event_Controller_Registration->__construct('Event Registrati…', true, 'null', null, 'false')    /var/www/wordpress/wp-content/plugins/civicrm/civicrm/CRM/Core/Invoke.php:314
3   CRM_Core_Invoke::runItem(Array) /var/www/wordpress/wp-content/plugins/civicrm/civicrm/CRM/Core/Invoke.php:69
4   CRM_Core_Invoke::_invoke(Array) /var/www/wordpress/wp-content/plugins/civicrm/civicrm/CRM/Core/Invoke.php:36
5   CRM_Core_Invoke::invoke(Array)  /var/www/wordpress/wp-content/plugins/civicrm/civicrm.php:1199
6   CiviCRM_For_WordPress->invoke() /var/www/wordpress/wp-content/plugins/civicrm/includes/civicrm.basepage.php:380
7   CiviCRM_For_WordPress_Basepage->basepage_handler(Object(WP))    /var/www/wordpress/wp-includes/class-wp-hook.php:307
8   WP_Hook->apply_filters(null, Array) /var/www/wordpress/wp-includes/class-wp-hook.php:331
9   WP_Hook->do_action(Array)   /var/www/wordpress/wp-includes/plugin.php:522
10  do_action_ref_array('wp', Array)    /var/www/wordpress/wp-includes/class-wp.php:771
11  WP->main('')    /var/www/wordpress/wp-includes/functions.php:1310
12  wp()    /var/www/wordpress/wp-blog-header.php:16
13  require('/var/www/wordpre…')    /var/www/wordpress/index.php:17
14  {main}

And the error that the users see is Sorry, due to an error, we are unable to fulfill your request at the moment. You may want to contact your administrator or service provider with more details about what action you were performing when this occurred. Could not find valid value for id

Note that I've looked at other questions and answers related to this, and, among others, I made sure that CiviCRM uses a valid Wordpress page in Administer -> System Settings -> CMS Database Integration (called 'civicrm'), that caching is disabled, and that clean URLS are activated, as they suggested.

The way I get to the event page is by first navigating to the list in https://mydomain.tld/civicrm/event/list/, and then selecting one event in the list.

I tried to also create a new blog post, insert the short code [civicrm component="event" id="8" action="info" mode="live" hijack="0"], and click on Register, but I get the very same error...

There's one comment that may be relevant, but I didn't understand how to act on; who knows, maybe it's relevant, but I don't know what it means to "re-enter the links to Events in the shortcode for the WP calendar".

Thanks in advance.

Answer 1

Partial success: If I set the Shortcode Display Mode setting to Remain in Shortcode Mode, then registration completes successfully without the error if I access the event via a short code.

However, I still get the error if I register to an event that I access via the list in https://mydomain.tld/civicrm/event/list/ (and then selecting one event in the list and clicking Register).

Answer 2

Can you also see if you have Cleaner URLs enabled?

This post CiviEvent - Error when registering: Could not find valid value for id details the settings and what issues that has fixed.

Cleaner URLs are the default now, but if your site has been upgraded from an older version they may not be enabled.

Answer 3

Are you using YOOtheme Pro? And its extension Essentials for YOOtheme by ZOOlanders?
Try deactivating the plugin: https://lab.civicrm.org/dev/core/-/issues/4394#note_92175