Perry Janssen Perry Janssen - 2 years ago 154
PHP Question

Drupal 8 Abstract method error when building a simple form

I'm new to Drupal and I want to build a simple form.
I get this error:

Fatal error: Class Drupal\medical\Form\LoginForm contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (Drupal\Core\Form\FormInterface::submitForm) in C:\xampp\htdocs\Webdevelopment\Burst\Drupal_Test\modules\medical\src\Form\LoginForm.php on line 8

Here's the code:


namespace Drupal\medical\Form;

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Form\FormBase;

class LoginForm extends FormBase {

public function getFormId(){
return 'medical_login';

public function buildForm(array $form, FormStateInterface $form_state) {
$form['username'] = array(
'#title' => t('Username'),
'#type' => 'textfield',
'#required' => TRUE,

$form['password'] = array(
'#title' => t('Password'),
'#type' => 'password',
'#required' => TRUE,

$form['submit'] = array(
'#type' => 'submit',
'#value' => 'Login',



What does this error mean exactly and how do I fix this?

Thanks :)

Answer Source

In the FormBase there are abstract methods which needs to implemented in child class i.e LoginForm. These are validate and submit methods ( in your case it is submitForm). write these methods in your LoginForm and this error will go

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