diff --git a/framework/Yii.php b/framework/Yii.php
index 4226770df37..124533958d3 100644
--- a/framework/Yii.php
+++ b/framework/Yii.php
@@ -5,8 +5,6 @@
  * @license http://www.yiiframework.com/license/
  */
 
-require __DIR__ . '/BaseYii.php';
-
 /**
  * Yii is a helper class serving common framework functionalities.
  *
diff --git a/framework/console/widgets/Table.php b/framework/console/widgets/Table.php
index 400a7313cb0..0a8f2b252f1 100644
--- a/framework/console/widgets/Table.php
+++ b/framework/console/widgets/Table.php
@@ -228,6 +228,7 @@ protected function renderRow(array $row, $spanLeft, $spanMiddle, $spanRight)
 
         $buffer = '';
         $arrayPointer = [];
+        $finalChunk = [];
         for ($i = 0, ($max = $this->calculateRowHeight($row)) ?: $max = 1; $i < $max; $i++) {
             $buffer .= $spanLeft . ' ';
             foreach ($size as $index => $cellSize) {
diff --git a/framework/helpers/BaseHtml.php b/framework/helpers/BaseHtml.php
index d8560a77676..5d7703556a6 100644
--- a/framework/helpers/BaseHtml.php
+++ b/framework/helpers/BaseHtml.php
@@ -1249,7 +1249,7 @@ private static function collectErrors($models, $encode, $showAllErrors)
         }
 
         if ($encode) {
-            for ($i = 0; $i < count($lines); $i++) {
+            for ($i = 0, $linesCount = count($lines); $i < $linesCount; $i++) {
                 $lines[$i] = Html::encode($lines[$i]);
             }
         }
diff --git a/framework/i18n/Formatter.php b/framework/i18n/Formatter.php
index f74b7a29f5f..f60c3807c31 100644
--- a/framework/i18n/Formatter.php
+++ b/framework/i18n/Formatter.php
@@ -1013,6 +1013,7 @@ public function asDuration($value, $implodeString = ', ', $negativeSign = '-')
             $isNegative = $interval->invert;
         }
 
+        $parts = [];
         if ($interval->y > 0) {
             $parts[] = Yii::t('yii', '{delta, plural, =1{1 year} other{# years}}', ['delta' => $interval->y], $this->locale);
         }
diff --git a/framework/validators/ExistValidator.php b/framework/validators/ExistValidator.php
index 0ba80228c45..b7e5c574abb 100644
--- a/framework/validators/ExistValidator.php
+++ b/framework/validators/ExistValidator.php
@@ -92,7 +92,7 @@ public function validateAttribute($model, $attribute)
     {
         $targetAttribute = $this->targetAttribute === null ? $attribute : $this->targetAttribute;
         $params = $this->prepareConditions($targetAttribute, $model, $attribute);
-        $conditions[] = $this->targetAttributeJunction == 'or' ? 'or' : 'and';
+        $conditions = [$this->targetAttributeJunction == 'or' ? 'or' : 'and'];
 
         if (!$this->allowArray) {
             foreach ($params as $key => $value) {
diff --git a/framework/validators/UniqueValidator.php b/framework/validators/UniqueValidator.php
index 89da62fde21..d99095cc126 100644
--- a/framework/validators/UniqueValidator.php
+++ b/framework/validators/UniqueValidator.php
@@ -121,7 +121,7 @@ public function validateAttribute($model, $attribute)
         $targetClass = $this->getTargetClass($model);
         $targetAttribute = $this->targetAttribute === null ? $attribute : $this->targetAttribute;
         $rawConditions = $this->prepareConditions($targetAttribute, $model, $attribute);
-        $conditions[] = $this->targetAttributeJunction === 'or' ? 'or' : 'and';
+        $conditions = [$this->targetAttributeJunction === 'or' ? 'or' : 'and'];
 
         foreach ($rawConditions as $key => $value) {
             if (is_array($value)) {