Issue #2940165 by mondrake, Berdir: [regression] Cannot add effects to image style via the UI

core/modules/image/src/ImageStyleListBuilder.php

@@ -39,9 +39,17 @@ public function getDefaultOperations(EntityInterface $entity) {
       'url' => $entity->urlInfo('flush-form'),
     ];
 
-    return parent::getDefaultOperations($entity) + [
+    $operations = parent::getDefaultOperations($entity) + [
       'flush' => $flush,
     ];
+
+    // Remove destination URL from the edit link to allow editing image
+    // effects.
+    if (isset($operations['edit'])) {
+      $operations['edit']['url'] = $entity->toUrl('edit-form');
+    }
+
+    return $operations;
   }
 
   /**

core/modules/image/src/Tests/ImageAdminStylesTest.php

@@ -422,9 +422,20 @@ public function testEditEffect() {
     // Edit the scale effect that was just added.
     $this->clickLink(t('Edit'));
     $this->drupalPostForm(NULL, ['data[width]' => '24', 'data[height]' => '19'], t('Update effect'));
-    $this->drupalPostForm(NULL, ['new' => 'image_scale'], t('Add'));
 
-    // Add another scale effect and make sure both exist.
+    // Add another scale effect and make sure both exist. Click through from
+    // the overview to make sure that it is possible to add new effect then.
+    $this->drupalGet('admin/config/media/image-styles');
+    $rows = $this->xpath('//table/tbody/tr');
+    $i = 0;
+    foreach ($rows as $row) {
+      if (((string) $row->td[0]) === 'Test style scale edit scale') {
+        $this->clickLink('Edit', $i);
+        break;
+      }
+      $i++;
+    }
+    $this->drupalPostForm(NULL, ['new' => 'image_scale'], t('Add'));
     $this->drupalPostForm(NULL, ['data[width]' => '12', 'data[height]' => '19'], t('Add effect'));
     $this->assertText(t('Scale 24×19'));
     $this->assertText(t('Scale 12×19'));