diff --git a/core/modules/filter/config/schema/filter.schema.yml b/core/modules/filter/config/schema/filter.schema.yml
index 6756f1e..74f2d35 100644
--- a/core/modules/filter/config/schema/filter.schema.yml
+++ b/core/modules/filter/config/schema/filter.schema.yml
@@ -52,13 +52,13 @@ filter_settings.filter_html:
   mapping:
     allowed_html:
       type: sequence
-      label: 'Allowed HTML'
+      label: 'Allowed HTML tags'
       sequence:
         type: sequence
-        label: 'Attributes'
+        label: 'Allowed attributes'
         sequence:
           type: string
-          label: 'Value'
+          label: 'Allowed attribute values'
     filter_html_help:
       type: boolean
       label: 'HTML help'
diff --git a/core/modules/filter/filter.install b/core/modules/filter/filter.install
index 92a460c..f179de7 100644
--- a/core/modules/filter/filter.install
+++ b/core/modules/filter/filter.install
@@ -21,7 +21,7 @@ function filter_update_dependencies() {
 /**
  * Update the filter_html filter format schema.
  */
-function filter_update_8001() {
+function filter_update_8401() {
   $config_factory = \Drupal::configFactory();
   foreach ($config_factory->listAll('filter.format.') as $name) {
     $filter = $config_factory->getEditable($name);
diff --git a/core/modules/filter/src/Plugin/Filter/FilterHtml.php b/core/modules/filter/src/Plugin/Filter/FilterHtml.php
index 527a5df..639de8e 100644
--- a/core/modules/filter/src/Plugin/Filter/FilterHtml.php
+++ b/core/modules/filter/src/Plugin/Filter/FilterHtml.php
@@ -87,13 +87,13 @@ public function preRenderAllowedHtml($element) {
    * {@inheritdoc}
    */
   public function setConfiguration(array $configuration) {
-    // The allowed_html setting is stored as a sequence of elements and
-    // attributes. The default configuration in the plugin annotation
-    // is deep merged into the actual configuration in FilterPluginCollection.
-    // So that we aren't deep merging the default configuration with the actual
-    // configuration of a plugin (thus making it impossible to remove an element
-    // in the list of defaults), we specify the default in the string
-    // representation and convert it to the stored array representation.
+    // The allowed_html setting is stored as a sequence of allowed HTML tags,
+    // each containing more configuration values. The default configuration in
+    // the plugin annotation is deep merged into the actual configuration in
+    // FilterPluginCollection. To prevent deep merging the default configuration
+    // with the actual configuration of a plugin (thus making it impossible to
+    // remove an element in the list of defaults), we specify the default in the
+    // string representation and convert it to the stored array representation.
     // @see \Drupal\filter\FilterPluginCollection::initializePlugin()
     if (is_string($configuration['settings']['allowed_html'])) {
       $configuration['settings']['allowed_html'] = static::convertAllowedHtmlStringToArray($configuration['settings']['allowed_html']);
@@ -106,6 +106,20 @@ public function setConfiguration(array $configuration) {
   /**
    * {@inheritdoc}
    */
+  public function defaultConfiguration() {
+    $default_configuration = parent::defaultConfiguration();
+    // Convert the string representation of the allowed_html setting to an
+    // array.
+    // @see ::setConfiguration()
+    if (is_string($default_configuration['settings']['allowed_html'])) {
+      $default_configuration['settings']['allowed_html'] = static::convertAllowedHtmlStringToArray($default_configuration['settings']['allowed_html']);
+    }
+    return $default_configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function process($text, $langcode) {
     $restrictions = $this->getHtmlRestrictions();
     // Split the work into two parts. For filtering HTML tags out of the content