Phone international error in submit form I installed the module (international phone) on drupal 8.6 and I display it on my form.
when sending data it gives me an error message and blocks sending data.
The website encountered an unexpected error. Please try again later.
Error: Class 'libphonenumber\PhoneNumberUtil' not found in Drupal\phone_international\Helpers\ValidatingService-&gt;isValidNumber() (line 24 of modules/phone_international/src/Helpers/ValidatingService.php).
Drupal\phone_international\Helpers\ValidatingService-&gt;isValidNumber('+212670998765') (Line: 74)
Drupal\phone_international\Plugin\Field\FieldWidget\PhoneInternationalDefaultWidget-&gt;phoneValidate(Array, Object, Array)
call_user_func_array(Array, Array) (Line: 282)
Drupal\Core\Form\FormValidator-&gt;doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator-&gt;doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator-&gt;doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator-&gt;doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator-&gt;doValidateForm(Array, Object, 'node_candidat_edit_form') (Line: 118)
Drupal\Core\Form\FormValidator-&gt;validateForm('node_candidat_edit_form', Array, Object) (Line: 575)
Drupal\Core\Form\FormBuilder-&gt;processForm('node_candidat_edit_form', Array, Object) (Line: 318)
Drupal\Core\Form\FormBuilder-&gt;buildForm('node_candidat_edit_form', Object) (Line: 93)
Drupal\Core\Controller\FormController-&gt;getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber-&gt;Drupal\Core\EventSubscriber{closure}() (Line: 582)
Drupal\Core\Render\Renderer-&gt;executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber-&gt;wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber-&gt;Drupal\Core\EventSubscriber{closure}() (Line: 151)
Symfony\Component\HttpKernel\HttpKernel-&gt;handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel-&gt;handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle-&gt;handle(Object, 1, 1) (Line: 99)
Drupal\page_cache\StackMiddleware\PageCache-&gt;pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache-&gt;handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware-&gt;handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware-&gt;handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel-&gt;handle(Object, 1, 1) (Line: 693)
Drupal\Core\DrupalKernel-&gt;handle(Object) (Line: 19)
The error suggests that you haven't followed the installation instructions on the module page:

Since the module requires an external library, Composer must be used.
composer require &quot;drupal/phone_international&quot;