AC-2883::Disable max session size in admin - Unable to login to admin anymore

Author: glo71317

lib/internal/Magento/Framework/Session/SaveHandler.php

@@ -126,7 +126,7 @@ public function read($sessionId): string
         $sessionMaxSize = $this->sessionMaxSizeConfig->getSessionMaxSize();
         $sessionSize = strlen($sessionData);
 
-        if ($sessionSize !== null && $sessionMaxSize < $sessionSize) {
+        if ($sessionMaxSize !== null && $sessionMaxSize < $sessionSize) {
             $sessionData = '';
             if ($this->appState->getAreaCode() === Area::AREA_FRONTEND) {
                 $this->messageManager->addErrorMessage(

lib/internal/Magento/Framework/Session/Test/Unit/SaveHandlerTest.php

@@ -132,7 +132,7 @@ public function testWriteMoreThanSessionMaxSize(): void
 
         $this->assertTrue($this->saveHandler->write("test_session_id", "testdata"));
     }
-    
+
     public function testReadMoreThanSessionMaxSize(): void
     {
         $this->sessionMaxSizeConfigMock
@@ -148,4 +148,20 @@ public function testReadMoreThanSessionMaxSize(): void
 
         $this->assertEquals(null, $this->saveHandler->read("test_session_id"));
     }
+
+    public function testReadSessionMaxZero(): void
+    {
+        $this->sessionMaxSizeConfigMock
+            ->expects($this->once())
+            ->method('getSessionMaxSize')
+            ->willReturn(0);
+
+        $this->saveHandlerAdapterMock
+            ->expects($this->once())
+            ->method('read')
+            ->with('test_session_id')
+            ->willReturn('test_session_data');
+
+        $this->assertEquals(null, $this->saveHandler->read("test_session_id"));
+    }
 }