diff --git a/modules/backend/behaviors/importexportcontroller/TranscodeFilter.php b/modules/backend/behaviors/importexportcontroller/TranscodeFilter.php
index bc683d600f..db6bffda90 100644
--- a/modules/backend/behaviors/importexportcontroller/TranscodeFilter.php
+++ b/modules/backend/behaviors/importexportcontroller/TranscodeFilter.php
@@ -17,7 +17,7 @@ class TranscodeFilter extends php_user_filter
 
     protected $encodingTo;
 
-    public function filter($in, $out, &$consumed, $closing)
+    public function filter($in, $out, &$consumed, bool $closing): int
     {
         while ($resource = stream_bucket_make_writeable($in)) {
             if (in_array($this->encodingFrom, mb_list_encodings())) {
@@ -42,7 +42,7 @@ public function filter($in, $out, &$consumed, $closing)
         return PSFS_PASS_ON;
     }
 
-    public function onCreate()
+    public function onCreate(): bool
     {
         if (strpos($this->filtername, self::FILTER_NAME) !== 0) {
             return false;
@@ -70,7 +70,7 @@ public function onCreate()
         return true;
     }
 
-    public function onClose()
+    public function onClose(): void
     {
         setlocale(LC_CTYPE, $this->params['locale']);
     }
diff --git a/modules/backend/classes/FilterScope.php b/modules/backend/classes/FilterScope.php
index 1fa39c4e5b..8f939dab06 100644
--- a/modules/backend/classes/FilterScope.php
+++ b/modules/backend/classes/FilterScope.php
@@ -104,7 +104,7 @@ public function __construct($scopeName, $label)
      * @param string $type Specifies a render mode as described above
      * @param array $config A list of render mode specific config.
      */
-    public function displayAs($type, $config = [])
+    public function displayAs(string $type, $config = [])
     {
         $this->type = strtolower($type) ?: $this->type;
         $this->config = $this->evalConfig($config);
diff --git a/modules/backend/classes/FormField.php b/modules/backend/classes/FormField.php
index 53c2a46efc..07143cf0d4 100644
--- a/modules/backend/classes/FormField.php
+++ b/modules/backend/classes/FormField.php
@@ -257,7 +257,7 @@ public function options($value = null)
      * @param string $type Specifies a render mode as described above
      * @param array $config A list of render mode specific config.
      */
-    public function displayAs($type, $config = [])
+    public function displayAs(string $type, $config = [])
     {
         if (in_array($type, ['textarea', 'widget'])) {
             // defaults to 'large'
diff --git a/modules/backend/classes/ListColumn.php b/modules/backend/classes/ListColumn.php
index 04bc867e48..5f31e6f2da 100644
--- a/modules/backend/classes/ListColumn.php
+++ b/modules/backend/classes/ListColumn.php
@@ -128,7 +128,7 @@ public function __construct($columnName, $label)
      * - number - numeric column, aligned right
      * @param string $type Specifies a render mode as described above
      */
-    public function displayAs($type, $config)
+    public function displayAs(string $type, $config)
     {
         $this->type = strtolower($type) ?: $this->type;
         $this->config = $this->evalConfig($config);
diff --git a/modules/backend/widgets/Filter.php b/modules/backend/widgets/Filter.php
index ce30f854d8..e0df6b7fec 100644
--- a/modules/backend/widgets/Filter.php
+++ b/modules/backend/widgets/Filter.php
@@ -711,7 +711,7 @@ public function removeScope($scopeName)
     protected function makeFilterScope($name, $config)
     {
         $label = $config['label'] ?? null;
-        $scopeType = $config['type'] ?? null;
+        $scopeType = $config['type'] ?? 'group';
 
         $scope = new FilterScope($name, $label);
         $scope->displayAs($scopeType, $config);
diff --git a/modules/backend/widgets/Form.php b/modules/backend/widgets/Form.php
index 5598810d93..056b895ed5 100644
--- a/modules/backend/widgets/Form.php
+++ b/modules/backend/widgets/Form.php
@@ -850,8 +850,8 @@ protected function makeFormField($name, $config = [])
          * Defined field type
          */
         else {
-            $fieldType = $config['type'] ?? null;
-            if (!is_string($fieldType) && $fieldType !== null) {
+            $fieldType = $config['type'] ?? 'text';
+            if (!is_string($fieldType)) {
                 throw new ApplicationException(Lang::get(
                     'backend::lang.field.invalid_type',
                     ['type' => gettype($fieldType)]
diff --git a/modules/backend/widgets/Lists.php b/modules/backend/widgets/Lists.php
index 2b3aa59b80..76d051f60a 100644
--- a/modules/backend/widgets/Lists.php
+++ b/modules/backend/widgets/Lists.php
@@ -1111,7 +1111,7 @@ protected function makeListColumn($name, $config)
             $config['searchable'] = false;
         }
 
-        $columnType = $config['type'] ?? null;
+        $columnType = $config['type'] ?? 'text';
 
         $column = new ListColumn($name, $label);
         $column->displayAs($columnType, $config);