diff --git a/src/Forms/GridField/SessionGridFieldStateManager.php b/src/Forms/GridField/SessionGridFieldStateManager.php
index 10ade3bec..750c1f336 100644
--- a/src/Forms/GridField/SessionGridFieldStateManager.php
+++ b/src/Forms/GridField/SessionGridFieldStateManager.php
@@ -18,7 +18,7 @@ class SessionGridFieldStateManager implements GridFieldStateManagerInterface, Gr
     protected function getStateID(GridField $gridField, $create = false): ?string
     {
         $requestVar = $this->getStateRequestVar();
-        $sessionStateID = $gridField->getForm()->getRequestHandler()->getRequest()->requestVar($requestVar);
+        $sessionStateID = $gridField->getForm()?->getRequestHandler()->getRequest()->requestVar($requestVar);
         if (!$sessionStateID) {
             $sessionStateID = Controller::curr()->getRequest()->requestVar($requestVar);
         }
@@ -63,7 +63,7 @@ class SessionGridFieldStateManager implements GridFieldStateManagerInterface, Gr
      */
     public function getStateKey(GridField $gridField): string
     {
-        $record = $gridField->getForm()->getRecord();
+        $record = $gridField->getForm()?->getRecord();
         return $gridField->getName() . '-' . ($record ? $record->ID : 0);
     }
 
diff --git a/tests/php/Forms/GridField/SessionGridFieldStateManagerTest.php b/tests/php/Forms/GridField/SessionGridFieldStateManagerTest.php
new file mode 100644
index 000000000..a296260d3
--- /dev/null
+++ b/tests/php/Forms/GridField/SessionGridFieldStateManagerTest.php
@@ -0,0 +1,131 @@
+<?php
+
+namespace SilverStripe\Forms\Tests\GridField;
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Control\HTTPRequest;
+use SilverStripe\Control\Session;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\Form;
+use SilverStripe\Forms\GridField\GridField;
+use SilverStripe\Forms\GridField\SessionGridFieldStateManager;
+use SilverStripe\Forms\Tests\GridField\GridFieldPrintButtonTest\TestObject;
+
+class SessionGridFieldStateManagerTest extends SapphireTest
+{
+    public function testStateKey()
+    {
+        $manager = new SessionGridFieldStateManager();
+        $controller = new Controller();
+        $form1 = new Form($controller, 'form1', new FieldList(), new FieldList());
+        $testObject = new TestObject();
+        $testObject->ID = 1;
+        $form2 = new Form($controller, 'form2', new FieldList(), new FieldList());
+        $form2->loadDataFrom($testObject);
+
+        $grid1 = new GridField('A');
+        $grid2 = new GridField('B');
+        $grid1->setForm($form1);
+        $grid2->setForm($form2);
+        $this->assertEquals('A-0', $manager->getStateKey($grid1));
+        $this->assertEquals('B-1', $manager->getStateKey($grid2));
+    }
+
+    public function testAddStateToURL()
+    {
+        $manager = new SessionGridFieldStateManager();
+        $grid = new GridField('TestGrid');
+        $grid->getState()->testValue = 'foo';
+        $stateRequestVar = $manager->getStateRequestVar();
+        $link = '/link-to/something';
+        $this->assertTrue(
+            preg_match(
+                "|^$link\?{$stateRequestVar}=[a-zA-Z0-9]+$|",
+                $manager->addStateToURL($grid, $link)
+            ) == 1
+        );
+
+        $link = '/link-to/something-else?someParam=somevalue';
+        $this->assertTrue(
+            preg_match(
+                "|^/link-to/something-else\?someParam=somevalue&{$stateRequestVar}=[a-zA-Z0-9]+$|",
+                $manager->addStateToURL($grid, $link)
+            ) == 1
+        );
+    }
+
+    public function testGetStateFromRequest()
+    {
+        $manager = new SessionGridFieldStateManager();
+
+        $session = new Session([]);
+        $request = new HTTPRequest(
+            'GET',
+            '/link-to/something',
+            [
+                $manager->getStateRequestVar() => 'testGetStateFromRequest'
+            ]
+        );
+        $request->setSession($session);
+
+        $controller = new Controller();
+        $controller->setRequest($request);
+        $controller->pushCurrent();
+        $form = new Form($controller, 'form1', new FieldList(), new FieldList());
+        $grid = new GridField('TestGrid');
+        $grid->setForm($form);
+
+        $grid->getState()->testValue = 'foo';
+        $state = $grid->getState(false)->Value() ?? '{}';
+        $result = $manager->getStateFromRequest($grid, $request);
+
+        $this->assertEquals($state, $result);
+        $controller->popCurrent();
+    }
+
+    public function testDefaultStateLeavesURLUnchanged()
+    {
+        $manager = new SessionGridFieldStateManager();
+        $grid = new GridField('DefaultStateGrid');
+        $grid->getState(false)->getData()->testValue->initDefaults(['foo' => 'bar']);
+        $link = '/link-to/something';
+
+        $this->assertEquals('{}', $grid->getState(false)->Value());
+
+        $this->assertEquals(
+            '/link-to/something',
+            $manager->addStateToURL($grid, $link)
+        );
+    }
+
+    public function testStoreState()
+    {
+        $manager = new SessionGridFieldStateManager();
+
+        $session = new Session([]);
+        $request = new HTTPRequest(
+            'GET',
+            '/link-to/something',
+            [
+                $manager->getStateRequestVar() => 'testStoreState'
+            ]
+        );
+        $request->setSession($session);
+
+        $controller = new Controller();
+        $controller->setRequest($request);
+        $controller->pushCurrent();
+        $form = new Form($controller, 'form1', new FieldList(), new FieldList());
+        $grid = new GridField('TestGrid');
+        $grid->setForm($form);
+
+        $grid->getState()->testValue = 'foo';
+        $state = $grid->getState(false)->Value() ?? '{}';
+
+        $manager->storeState($grid);
+        $this->assertEquals($state, $session->get('testStoreState')['TestGrid-0']);
+
+        $controller->popCurrent();
+    }
+}