Title: Error when validating form
Last modified: October 22, 2025

---

# Error when validating form

 *  Resolved [philonbass](https://wordpress.org/support/users/philonbass/)
 * (@philonbass)
 * [5 months, 3 weeks ago](https://wordpress.org/support/topic/error-when-validating-form/)
 * I get an error “_A variable mismatch has been detected_” when a user tries to
   save the form and a field which needs to be validated is empty. When I remove
   the validation from the field, the form is being saved. I found the following
   in the file “pdb_debugging_65e88af9425eb.txt”
 *     ```wp-block-code
       <header>[10/22/25 3:19pm UTC]</header> <pre>trim(): Passing null to parameter #1 ($string) of type string is deprecated</pre><footer>in /home/xyz/wp-content/plugins/participants-database/classes/xnau_FormValidation.php on line 429</footer>
       ```
   
 * Can you investigate on this behaviour? 
   participants-database v.2.7.7pdb-image-
   expansion v.1.7.6pdb-login v2.2
 * Thanks, Phil
    -  This topic was modified 5 months, 3 weeks ago by [philonbass](https://wordpress.org/support/users/philonbass/).
    -  This topic was modified 5 months, 3 weeks ago by [philonbass](https://wordpress.org/support/users/philonbass/).

Viewing 5 replies - 1 through 5 (of 5 total)

 *  Plugin Author [rolandbarker](https://wordpress.org/support/users/rolandbarker/)
 * (@rolandbarker)
 * [5 months, 3 weeks ago](https://wordpress.org/support/topic/error-when-validating-form/#post-18691805)
 * What is the intended effect of the validation? What is the validation setting
   for the field?
 * The item in the error log is not causing a problem, it’s only a warning.
 *  Thread Starter [philonbass](https://wordpress.org/support/users/philonbass/)
 * (@philonbass)
 * [5 months, 3 weeks ago](https://wordpress.org/support/topic/error-when-validating-form/#post-18692249)
 * Its hard to explain without screenshots. The validation is for a required filed
   like “address” that needs to be filled out before the form can be submitted. 
   if the form does have one required field and this is not filled in, the error
   occurs.
    -  This reply was modified 5 months, 3 weeks ago by [philonbass](https://wordpress.org/support/users/philonbass/).
    -  This reply was modified 5 months, 3 weeks ago by [philonbass](https://wordpress.org/support/users/philonbass/).
 *  Thread Starter [philonbass](https://wordpress.org/support/users/philonbass/)
 * (@philonbass)
 * [5 months, 3 weeks ago](https://wordpress.org/support/topic/error-when-validating-form/#post-18692665)
 * I found out, that the validation does not work when the url ends with “?pid=KTCQOMLVV67VHGTJ”.
   But when the form is submitted the url changes to “?sess=e2c492dca29fa9d5975a8d00bc1d7a98”
   at the ending. Then the validation works as usual.
 *  Plugin Author [rolandbarker](https://wordpress.org/support/users/rolandbarker/)
 * (@rolandbarker)
 * [5 months, 3 weeks ago](https://wordpress.org/support/topic/error-when-validating-form/#post-18693124)
 * So, from what I am seeing here, the validation is working, if a required field
   is left empty, it will trigger a validation error. I don’t recognize the validation
   error message, so this is probably the custom validation message you have set
   for the required field.
 * So, I’m sorry, but I still don’t understand the problem. I’m trying to understand
   what you want it to do that it isn’t doing.
 *  Thread Starter [philonbass](https://wordpress.org/support/users/philonbass/)
 * (@philonbass)
 * [5 months, 2 weeks ago](https://wordpress.org/support/topic/error-when-validating-form/#post-18695000)
 * There seems to have been a temporary problem with either the server or something
   else, but now everything is back to normal and working fine. Sorry for the inconvenience.

Viewing 5 replies - 1 through 5 (of 5 total)

You must be [logged in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Ferror-when-validating-form%2F%3Foutput_format%3Dmd&locale=en_US)
to reply to this topic.

 * ![](https://ps.w.org/participants-database/assets/icon-256x256.jpg?rev=1389807)
 * [Participants Database](https://wordpress.org/plugins/participants-database/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/participants-database/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/participants-database/)
 * [Active Topics](https://wordpress.org/support/plugin/participants-database/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/participants-database/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/participants-database/reviews/)

 * 5 replies
 * 2 participants
 * Last reply from: [philonbass](https://wordpress.org/support/users/philonbass/)
 * Last activity: [5 months, 2 weeks ago](https://wordpress.org/support/topic/error-when-validating-form/#post-18695000)
 * Status: resolved