diff --git a/core/attributedef.class.inc.php b/core/attributedef.class.inc.php
index 823cfa93cb..40797d2706 100644
--- a/core/attributedef.class.inc.php
+++ b/core/attributedef.class.inc.php
@@ -8599,7 +8599,7 @@ class AttributeBlob extends AttributeDefinition
 	public function RecordAttChange(DBObject $oObject, $original, $value): void
 	{
 		// N°6502 Don't record history if only the download count has changed
-		if ($original->EqualsExceptDownloadsCount($value)) {
+		if ((null !== $original) && (null !== $value) && $original->EqualsExceptDownloadsCount($value)) {
 			return;
 		}
 
diff --git a/tests/php-unit-tests/unitary-tests/core/ormDocumentTest.php b/tests/php-unit-tests/unitary-tests/core/ormDocumentTest.php
new file mode 100644
index 0000000000..e9d33871c3
--- /dev/null
+++ b/tests/php-unit-tests/unitary-tests/core/ormDocumentTest.php
@@ -0,0 +1,142 @@
+<?php
+/*!
+ * @copyright   Copyright (C) 2010-2023 Combodo SARL
+ * @license     http://opensource.org/licenses/AGPL-3.0
+ */
+
+namespace Combodo\iTop\Test\UnitTest\Core;
+
+use Combodo\iTop\Test\UnitTest\ItopDataTestCase;
+use ormDocument;
+
+/**
+ * Tests of the ormDocument class
+ */
+class ormDocumentTest extends ItopDataTestCase
+{
+	/**
+	 * @inheritDoc
+	 */
+	protected function LoadRequiredItopFiles(): void
+	{
+		parent::LoadRequiredItopFiles();
+
+		$this->RequireOnceItopFile('core/ormdocument.class.inc.php');
+	}
+
+
+	/**
+	 * @param array $aDocAData
+	 * @param array $aDocBData
+	 * @param bool $bExpectedResult
+	 *
+	 * @dataProvider EqualsExceptDownloadsCountProvider
+	 */
+	public function testEqualsExceptDownloadsCount(array $aDocAData, array $aDocBData, bool $bExpectedResult)
+	{
+		$oDocA = new ormDocument(base64_decode($aDocAData[0]), $aDocAData[1], $aDocAData[2], $aDocAData[3]);
+		$oDocB = new ormDocument(base64_decode($aDocBData[0]), $aDocBData[1], $aDocBData[2], $aDocBData[3]);
+
+		$bTestedResult = $oDocA->EqualsExceptDownloadsCount($oDocB);
+		$this->assertSame($bExpectedResult, $bTestedResult);
+	}
+
+	public function EqualsExceptDownloadsCountProvider(): array
+	{
+		$sFirstDummyTextFileContentBase64 = "Rmlyc3Q=";
+		$sSecondDummyTextFileContentBase64 = "U2Vjb25k";
+
+		return [
+			'Total different files' => [
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				[
+					$sSecondDummyTextFileContentBase64,
+					"image/png",
+					"b.png",
+					1
+				],
+				false,
+			],
+			'Different data only' => [
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				[
+					$sSecondDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				false,
+			],
+			'Different mime types only' => [
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				[
+					$sFirstDummyTextFileContentBase64,
+					"image/png",
+					"a.txt",
+					0
+				],
+				false,
+			],
+			'Different file names only' => [
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"b.txt",
+					0
+				],
+				false,
+			],
+			'Different download counts only' => [
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					1
+				],
+				true,
+			],
+			'Identical files, different object instances' => [
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				[
+					$sFirstDummyTextFileContentBase64,
+					"text/plain",
+					"a.txt",
+					0
+				],
+				false,
+			],
+		];
+	}
+}