diff --git a/src/Plugin/Field/FieldWidget/InlineParagraphsWidget.php b/src/Plugin/Field/FieldWidget/InlineParagraphsWidget.php
index c56e58f..6348939 100644
--- a/src/Plugin/Field/FieldWidget/InlineParagraphsWidget.php
+++ b/src/Plugin/Field/FieldWidget/InlineParagraphsWidget.php
@@ -730,8 +730,7 @@ class InlineParagraphsWidget extends WidgetBase {
 
     // Add 'add more' button, if not working with a programmed form.
     if (($real_item_count < $cardinality || $cardinality == FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED) && !$form_state->isProgrammed()) {
-      // Hide the button when translating.
-      $add_more_access = $this->getCurrentLangcode($form_state, $items) == $items->getEntity()->getUntranslated()->language()->getId();
+      $add_more_access = $this->addMoreAccess($items, $form_state);
       $elements['add_more'] = array(
         '#type' => 'container',
         '#theme_wrappers' => array('paragraphs_dropbutton_wrapper'),
@@ -838,6 +837,13 @@ class InlineParagraphsWidget extends WidgetBase {
    * @return string
    */
   protected function getCurrentLangcode(FormStateInterface $form_state, FieldItemListInterface $items) {
+    // The form and the parent entity have a locked language
+    // (\Drupal\Core\Language::LANGCODE_NOT_SPECIFIED is most cases). Use the
+    // current interface language instead.
+    if ($form_state->get('langcode') && \Drupal::languageManager()->getLanguage($form_state->get('langcode'))->isLocked()){
+      return \Drupal::languageManager()->getCurrentLanguage()->getId();
+    }
+
     return $form_state->get('langcode') ?: $items->getEntity()->language()->getId();
   }
 
@@ -1097,4 +1103,20 @@ class InlineParagraphsWidget extends WidgetBase {
     }
     return $values;
   }
+
+  /**
+   * Check access to the add more button.
+   *
+   * @param \Drupal\Core\Field\FieldItemListInterface $items
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *
+   * @return bool
+   */
+  protected function addMoreAccess(FieldItemListInterface $items, FormStateInterface $form_state) {
+    // Hide the button when translating.
+    if (!$items->getEntity()->getEntityType()->isTranslatable()) {
+      return TRUE;
+    }
+    return $this->getCurrentLangcode($form_state, $items) == $items->getEntity()->getUntranslated()->language()->getId();
+  }
 }
diff --git a/src/Tests/ParagraphsTranslationTest.php b/src/Tests/ParagraphsTranslationTest.php
index 4075edd..ecb1398 100644
--- a/src/Tests/ParagraphsTranslationTest.php
+++ b/src/Tests/ParagraphsTranslationTest.php
@@ -86,6 +86,12 @@ class ParagraphsTranslationTest extends WebTestBase {
     $this->drupalPostForm(NULL, $edit, t('Save and keep published'));
     $this->assertNoText(t('Example published and unpublished'));
 
+    //Add paragraphed content with untranslatable language
+    $this->drupalGet('node/add/paragraphed_content_demo');
+    $edit = array('langcode[0][value]' => 'und');
+    $this->drupalPostForm(NULL, $edit, t('Add Text + Image'));
+    $this->assertResponse(200);
+
     // Add paragraphed content.
     $this->drupalGet('node/add/paragraphed_content_demo');
     $this->drupalPostForm(NULL, NULL, t('Add Text + Image'));