diff --git a/moto/cloudformation/models.py b/moto/cloudformation/models.py
index d3fb2870d..d3f0976a1 100644
--- a/moto/cloudformation/models.py
+++ b/moto/cloudformation/models.py
@@ -707,6 +707,7 @@ class CloudFormationBackend(BaseBackend):
             for stack in self.stacks.values():
                 if stack.name == name_or_stack_id:
                     return stack
+            raise ValidationError(name_or_stack_id)
 
     def update_stack(self, name, template, role_arn=None, parameters=None, tags=None):
         stack = self.get_stack(name)
@@ -715,8 +716,6 @@ class CloudFormationBackend(BaseBackend):
 
     def list_stack_resources(self, stack_name_or_id):
         stack = self.get_stack(stack_name_or_id)
-        if stack is None:
-            return None
         return stack.stack_resources
 
     def delete_stack(self, name_or_stack_id):
diff --git a/moto/cloudformation/responses.py b/moto/cloudformation/responses.py
index 4c8ad36d0..6d2af655d 100644
--- a/moto/cloudformation/responses.py
+++ b/moto/cloudformation/responses.py
@@ -232,8 +232,6 @@ class CloudFormationResponse(BaseResponse):
             if stack_resource.logical_resource_id == logical_resource_id:
                 resource = stack_resource
                 break
-        else:
-            raise ValidationError(logical_resource_id)
 
         template = self.response_template(DESCRIBE_STACK_RESOURCE_RESPONSE_TEMPLATE)
         return template.render(stack=stack, resource=resource)
@@ -267,9 +265,6 @@ class CloudFormationResponse(BaseResponse):
         stack_name_or_id = self._get_param("StackName")
         resources = self.cloudformation_backend.list_stack_resources(stack_name_or_id)
 
-        if resources is None:
-            raise ValidationError(stack_name_or_id)
-
         template = self.response_template(LIST_STACKS_RESOURCES_RESPONSE)
         return template.render(resources=resources)
 
diff --git a/tests/test_cloudformation/test_cloudformation_stack_crud.py b/tests/test_cloudformation/test_cloudformation_stack_crud.py
index 40004f805..1725be0f6 100644
--- a/tests/test_cloudformation/test_cloudformation_stack_crud.py
+++ b/tests/test_cloudformation/test_cloudformation_stack_crud.py
@@ -570,6 +570,15 @@ def test_describe_stack_events_shows_create_update_and_delete():
 
     list(stack_events_to_look_for).should.be.empty
 
+    with pytest.raises(BotoServerError) as exp:
+        conn.describe_stack_events("non_existing_stack")
+    err = exp.value
+    err.message.should.equal("Stack with id non_existing_stack does not exist")
+    err.body.should.match(r"Stack with id non_existing_stack does not exist")
+    err.error_code.should.equal("ValidationError")
+    err.reason.should.equal("Bad Request")
+    err.status.should.equal(400)
+
 
 @mock_cloudformation_deprecated
 def test_create_stack_lambda_and_dynamodb():
diff --git a/tests/test_cloudformation/test_cloudformation_stack_crud_boto3.py b/tests/test_cloudformation/test_cloudformation_stack_crud_boto3.py
index 3eb2c7291..0fa45e1b8 100644
--- a/tests/test_cloudformation/test_cloudformation_stack_crud_boto3.py
+++ b/tests/test_cloudformation/test_cloudformation_stack_crud_boto3.py
@@ -255,6 +255,7 @@ def test_boto3_filter_stacks():
     conn.create_stack(StackName="test_stack", TemplateBody=dummy_template_json)
     conn.create_stack(StackName="test_stack2", TemplateBody=dummy_template_json)
     conn.update_stack(StackName="test_stack", TemplateBody=dummy_template_json2)
+
     stacks = conn.list_stacks(StackStatusFilter=["CREATE_COMPLETE"])
     stacks.get("StackSummaries").should.have.length_of(1)
     stacks = conn.list_stacks(StackStatusFilter=["UPDATE_COMPLETE"])
@@ -318,6 +319,18 @@ def test_boto3_describe_stack_set_operation():
 
     response["StackSetOperation"]["Status"].should.equal("STOPPED")
     response["StackSetOperation"]["Action"].should.equal("CREATE")
+    with pytest.raises(ClientError) as exp:
+        cf_conn.describe_stack_set_operation(
+            StackSetName="test_stack_set", OperationId="non_existing_operation"
+        )
+    exp_err = exp.value.response.get("Error")
+    exp_metadata = exp.value.response.get("ResponseMetadata")
+
+    exp_err.get("Code").should.match(r"ValidationError")
+    exp_err.get("Message").should.match(
+        r"Stack with id non_existing_operation does not exist"
+    )
+    exp_metadata.get("HTTPStatusCode").should.equal(400)
 
 
 @mock_cloudformation
@@ -1136,6 +1149,16 @@ def test_delete_change_set():
     cf_conn.delete_change_set(ChangeSetName="NewChangeSet", StackName="NewStack")
     cf_conn.list_change_sets(StackName="NewStack")["Summaries"].should.have.length_of(0)
 
+    # Testing deletion by arn
+    result = cf_conn.create_change_set(
+        StackName="NewStack",
+        TemplateBody=dummy_template_json,
+        ChangeSetName="NewChangeSet1",
+        ChangeSetType="CREATE",
+    )
+    cf_conn.delete_change_set(ChangeSetName=result.get("Id"), StackName="NewStack")
+    cf_conn.list_change_sets(StackName="NewStack")["Summaries"].should.have.length_of(0)
+
 
 @mock_cloudformation
 @mock_ec2
@@ -1309,6 +1332,19 @@ def test_stack_events():
 
     list(stack_events_to_look_for).should.be.empty
 
+    with pytest.raises(ClientError) as exp:
+        stack = cf.Stack("non_existing_stack")
+        events = list(stack.events.all())
+
+    exp_err = exp.value.response.get("Error")
+    exp_metadata = exp.value.response.get("ResponseMetadata")
+
+    exp_err.get("Code").should.match(r"ValidationError")
+    exp_err.get("Message").should.match(
+        r"Stack with id non_existing_stack does not exist"
+    )
+    exp_metadata.get("HTTPStatusCode").should.equal(400)
+
 
 @mock_cloudformation
 def test_list_exports():