Body: <p>We ran into this problem today after updating to 5.78.4, and I confirmed that it is happening the same way on <a href="https://dmaster.demo.civicrm.org/" rel="nofollow noreferrer">https://dmaster.demo.civicrm.org/</a></p>
  <p>If you create a custom field of type Contact Reference and have it be multiselect, if you try to submit the form without any value in the field you get an error. Having a user or multiple users there it works fine, but without it I get:</p>
  <pre><code>CRM_Core_Exception:  is not of type String in vendor/civicrm/civicrm-core/CRM/Core/DAO.php on line 1732
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-11-04T19:10:23.423Z
Comments.Text: Might be the same as https://lab.civicrm.org/dev/core/-/issues/5555 ?
Comments.UserDisplayName: Demerit
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-11-04T19:22:55.637Z
Comments.Text: That looks like it exactly, thank you! I looked there, but didn't find it.
Comments.UserDisplayName: zip
Tags: <custom-fields><error><core>
Title: Bug - I think - with the Contact Reference field type when it is multiselect
ThreadText: # Bug - I think - with the Contact Reference field type when it is multiselect
  
  (Asked by: username_0 on 2024-11-04)
  
  We ran into this problem today after updating to 5.78.4, and I confirmed that it is happening the same way on https://dmaster.demo.civicrm.org/
  If you create a custom field of type Contact Reference and have it be multiselect, if you try to submit the form without any value in the field you get an error. Having a user or multiple users there it works fine, but without it I get:
  CRM_Core_Exception:  is not of type String in vendor/civicrm/civicrm-core/CRM/Core/DAO.php on line 1732
  
  **Tags:** custom-fields, error, core
  
  > **Comments:**
  > **username_1**: Might be the same as https://lab.civicrm.org/dev/core/-/issues/5555 ?  
  > **username_0**: That looks like it exactly, thank you! I looked there, but didn't find it.  
  
  ---
  
  ## 0 answers
  
  