diff --git a/library/think/Model.php b/library/think/Model.php
index 9024c30c..2e5531e5 100644
--- a/library/think/Model.php
+++ b/library/think/Model.php
@@ -1258,7 +1258,7 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
     /**
      * 返回模型的错误信息
      * @access public
-     * @return string
+     * @return string|array
      */
     public function getError()
     {
diff --git a/library/think/model/relation/BelongsTo.php b/library/think/model/relation/BelongsTo.php
index 9e443d54..630719c0 100644
--- a/library/think/model/relation/BelongsTo.php
+++ b/library/think/model/relation/BelongsTo.php
@@ -54,7 +54,10 @@ class BelongsTo extends OneToOne
             ->where($this->localKey, $this->parent->$foreignKey)
             ->relation($subRelation)
             ->find();
-        $relationModel->setParent(clone $this->parent);
+
+        if ($relationModel) {
+            $relationModel->setParent(clone $this->parent);
+        }
 
         return $relationModel;
     }
diff --git a/library/think/model/relation/HasOne.php b/library/think/model/relation/HasOne.php
index 991a594f..e5a557a0 100644
--- a/library/think/model/relation/HasOne.php
+++ b/library/think/model/relation/HasOne.php
@@ -51,7 +51,10 @@ class HasOne extends OneToOne
         }
         // 判断关联类型执行查询
         $relationModel = $this->query->where($this->foreignKey, $this->parent->$localKey)->relation($subRelation)->find();
-        $relationModel->setParent(clone $this->parent);
+
+        if ($relationModel) {
+            $relationModel->setParent(clone $this->parent);
+        }
 
         return $relationModel;
     }
diff --git a/library/think/model/relation/MorphOne.php b/library/think/model/relation/MorphOne.php
index b58b0419..e22198bb 100644
--- a/library/think/model/relation/MorphOne.php
+++ b/library/think/model/relation/MorphOne.php
@@ -56,7 +56,10 @@ class MorphOne extends Relation
             call_user_func_array($closure, [ & $this->query]);
         }
         $relationModel = $this->relation($subRelation)->find();
-        $relationModel->setParent(clone $this->parent);
+
+        if ($relationModel) {
+            $relationModel->setParent(clone $this->parent);
+        }
 
         return $relationModel;
     }
diff --git a/library/think/model/relation/MorphTo.php b/library/think/model/relation/MorphTo.php
index 70f1dc03..d67989c4 100644
--- a/library/think/model/relation/MorphTo.php
+++ b/library/think/model/relation/MorphTo.php
@@ -58,7 +58,10 @@ class MorphTo extends Relation
         // 主键数据
         $pk            = $this->parent->$morphKey;
         $relationModel = (new $model)->relation($subRelation)->find($pk);
-        $relationModel->setParent(clone $this->parent);
+
+        if ($relationModel) {
+            $relationModel->setParent(clone $this->parent);
+        }
         return $relationModel;
     }