Answers.Body: <p>I solved it in a very unusual way - I added this rewrite on .htaccess file:</p>
  
  <pre><code>RewriteEngine on
  RewriteCond %{HTTP_HOST} ^www\.terranova.tamera\.org [NC]
  RewriteRule ^(.*)$ https://terranova.tamera.org/$1 [L,R=301]
  </code></pre>
  
  <p>To unify all accesses to use the non-www url.
  For a reason I cannot yet explain, this completely resolved the issue.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-05-16T15:44:26.617Z
Answers.LastActivityDate: 2019-05-16T15:44:26.617Z
Answers.UserDisplayName: Elad
Body: <p>I am running CiviCRM 5.10.0 on Drupal, and I see the following scenario happening, very consistently:</p>
  
  <ol>
  <li>go to one of my event registration forms: <a href="https://www.terranova.tamera.org/de/civicrm/event/register?reset=1&amp;id=1994" rel="nofollow noreferrer">https://www.terranova.tamera.org/de/civicrm/event/register?reset=1&amp;id=1994</a></li>
  <li>submit the form although many required fields are still missing.</li>
  <li>Form refreshes with all validation errors. Notice that the url has changed and lost its 'id' param, for the current event.</li>
  <li>complete the registration form correctly and try to submit again.</li>
  <li>Receive an error saying: 
  Sorry, due to an error, we are unable to fulfill... 
  <strong>Could not find valid value for id</strong></li>
  </ol>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2019-05-16T12:01:59.073Z
Comments.Text: I just tried on 5.13.4 and it works. There must be some custom module/plugin/extension that is resetting the id from session.
Comments.UserDisplayName: Pradeep Nayak
Tags: <civievent><error><online-registration>
Title: Event registration form loses 'id' url param and then throws an exception
ThreadText: # Event registration form loses 'id' url param and then throws an exception
  
  (Asked by: username_0 on 2019-05-16)
  
  I am running CiviCRM 5.10.0 on Drupal, and I see the following scenario happening, very consistently:
  
  1. go to one of my event registration forms: <https://www.terranova.tamera.org/de/civicrm/event/register?reset=1&id=1994>
  2. submit the form although many required fields are still missing.
  3. Form refreshes with all validation errors. Notice that the url has changed and lost its 'id' param, for the current event.
  4. complete the registration form correctly and try to submit again.
  5. Receive an error saying:
     Sorry, due to an error, we are unable to fulfill...
     **Could not find valid value for id**
  
  **Tags:** civievent, error, online-registration
  
  > **Comments:**
  > **username_1**: I just tried on 5.13.4 and it works. There must be some custom module/plugin/extension that is resetting the id from session.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_0 on 2019-05-16. Score: 1
  
  I solved it in a very unusual way - I added this rewrite on .htaccess file:
  
  ```
  RewriteEngine on
  RewriteCond %{HTTP_HOST} ^www\.terranova.tamera\.org [NC]
  RewriteRule ^(.*)$ https://terranova.tamera.org/$1 [L,R=301]
  
  ```
  
  To unify all accesses to use the non-www url.
  For a reason I cannot yet explain, this completely resolved the issue.
  
  
  ---
  
  