Fix #17974: Fix ActiveRelationTrait compatibility with PHP 7.4

framework/CHANGELOG.md

@@ -9,6 +9,7 @@ Yii Framework 2 Change Log
 - Bug #17942: Fix for `DbCache` loop in MySQL `QueryBuilder` (alex-code)
 - Bug #17960: Fix unsigned primary key type mapping for SQLite (bizley)
 - Enh #17758: `Query::withQuery()` can be used for CTE (sartor)
+- Bug #17974: Fix ActiveRelationTrait compatibility with PHP 7.4 (Ximich)
 
 
 2.0.34 March 26, 2020

framework/db/ActiveRelationTrait.php

@@ -242,7 +242,7 @@ trait ActiveRelationTrait
                 $viaQuery->asArray($this->asArray);
             }
             $viaQuery->primaryModel = null;
-            $viaModels = $viaQuery->populateRelation($viaName, $primaryModels);
+            $viaModels = array_filter($viaQuery->populateRelation($viaName, $primaryModels));
             $this->filterByModels($viaModels);
         } else {
             $this->filterByModels($primaryModels);