Unexpected error after saving configuration

Hello,
I'm using Search API attachments to search in my files, with a Solr hosting. The Solr search on fields (like title) is working.

After enabling the module, I've added the following config on config/search/search_api_attachments:
Extraction method: Solr Extractor
Solr server: 'my solr server'
Tika path: update/extract (default)

After submit I get the following error:

The website encountered an unexpected error. Please try again later.
Error: Call to undefined method Drupal\search_api_solr\Plugin\search_api\backend\SearchApiSolrBackend::getSolrConnection() in Drupal\search_api_attachments\Plugin\search_api_attachments\SolrExtractor->extract() (line 79 of modules/contrib/search_api_attachments/src/Plugin/search_api_attachments/SolrExtractor.php).
Drupal\search_api_attachments\Plugin\search_api_attachments\SolrExtractor->extract(Object) (Line: 159)
Drupal\search_api_attachments\Form\TextExtractorFormSettings->submitForm(Array, Object)
call_user_func_array(Array, Array) (Line: 111)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers(Array, Object) (Line: 51)
Drupal\Core\Form\FormSubmitter->doSubmitForm(Array, Object) (Line: 583)
Drupal\Core\Form\FormBuilder->processForm('search_api_attachments_admin_form', Array, Object) (Line: 314)
Drupal\Core\Form\FormBuilder->buildForm('search_api_attachments_admin_form', Object) (Line: 74)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 574)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
call_user_func_array(Object, Array) (Line: 144)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 64)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 99)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 50)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 652)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)