You may encounter this error when you're trying to disable or delete a custom field.

When setting up single sign-on (SSO) for Directory apps and custom SAML apps, a value called Name ID can be passed from Zoho Directory to the application. The application will use this Name ID to identify the user trying to sign in. This value will usually be the Primary Email Address. But you can also pass any user information field in Zoho Directory as the Name ID. Learn more about setting Name IDs

If the Name ID is not passed to an app, SSO for the app might fail. So you will not be allowed to disable or delete a custom field if the custom field is set as the Name ID of a Directory or a custom app.

1. Sign in to Zoho Directory.
   
2. Click Admin Panel in the left menu.
   
3. Click Users, then click the Manage Fields tab.
   
4. Hover over the custom field you're trying to delete, click , then click Disable or Delete. You will be shown an error message containing the list of apps in which this custom field is being used.
   
   
5. Note down the names of the apps.
   
6. Click Applications in the left menu, then click on the app that is blocking the field from being deleted.
   
7. Go to the Single Sign-On tab, then click on the Service Provider Details in the tab.
   
8. In the Credential Details section, check if the Application Username field is set as the custom field, or as Custom.
   
1. If it is set as the custom field, change it to something else.
   
2. If it is set as Custom, edit the Expression Value field and reconstruct the expression to exclude the custom field.
   
Note: This action might disrupt SSO and prevent your users from signing in to the app. Ensure you make the changes carefully on both Zoho Directory and the SSO app to avoid service disruption.

9. Repeat steps 6-8 to remove the custom field from all the required apps.
   
10. Try disabling or deleting the custom field again using steps 1-4.