[Serializer] Improve messages for unexpected resources values

src/Symfony/Component/Serializer/Encoder/XmlEncoder.php

@@ -426,7 +426,7 @@ class XmlEncoder extends SerializerAwareEncoder implements EncoderInterface, Dec
             return $this->appendNode($parentNode, $data, 'data');
         }
 
-        throw new NotEncodableValueException(sprintf('An unexpected value could not be serialized: %s', var_export($data, true)));
+        throw new NotEncodableValueException(sprintf('An unexpected value could not be serialized: %s', !\is_resource($data) ? var_export($data, true) : sprintf('%s resource', get_resource_type($data))));
     }
 
     /**

src/Symfony/Component/Serializer/Serializer.php

@@ -164,7 +164,7 @@ class Serializer implements SerializerInterface, NormalizerInterface, Denormaliz
             throw new NotNormalizableValueException(sprintf('Could not normalize object of type %s, no supporting normalizer found.', \get_class($data)));
         }
 
-        throw new NotNormalizableValueException(sprintf('An unexpected value could not be normalized: %s', var_export($data, true)));
+        throw new NotNormalizableValueException(sprintf('An unexpected value could not be normalized: %s', !\is_resource($data) ? var_export($data, true) : sprintf('%s resource', get_resource_type($data))));
     }
 
     /**

src/Symfony/Component/Serializer/Tests/Encoder/XmlEncoderTest.php

@@ -14,6 +14,7 @@ namespace Symfony\Component\Serializer\Tests\Encoder;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Serializer\Encoder\XmlEncoder;
+use Symfony\Component\Serializer\Exception\NotEncodableValueException;
 use Symfony\Component\Serializer\Normalizer\CustomNormalizer;
 use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
 use Symfony\Component\Serializer\Serializer;
@@ -679,6 +680,14 @@ XML;
         $this->assertEquals($this->createXmlWithDateTimeField(), $actualXml);
     }
 
+    public function testNotEncodableValueExceptionMessageForAResource()
+    {
+        $this->expectException(NotEncodableValueException::class);
+        $this->expectExceptionMessage('An unexpected value could not be serialized: stream resource');
+
+        (new XmlEncoder())->encode(tmpfile(), 'xml');
+    }
+
     /**
      * @return XmlEncoder
      */

src/Symfony/Component/Serializer/Tests/SerializerTest.php

@@ -13,6 +13,7 @@ namespace Symfony\Component\Serializer\Tests;
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Serializer\Encoder\JsonEncoder;
+use Symfony\Component\Serializer\Exception\NotNormalizableValueException;
 use Symfony\Component\Serializer\Normalizer\ArrayDenormalizer;
 use Symfony\Component\Serializer\Normalizer\CustomNormalizer;
 use Symfony\Component\Serializer\Normalizer\DenormalizerAwareInterface;
@@ -328,6 +329,14 @@ class SerializerTest extends TestCase
 
         $this->assertEquals(new Foo(new Bar('baz')), $serializer->deserialize($jsonData, Foo::class, 'json'));
     }
+
+    public function testNotNormalizableValueExceptionMessageForAResource()
+    {
+        $this->expectException(NotNormalizableValueException::class);
+        $this->expectExceptionMessage('An unexpected value could not be normalized: stream resource');
+
+        (new Serializer())->normalize(tmpfile());
+    }
 }
 
 class Model