diff --git a/core/log.class.inc.php b/core/log.class.inc.php
index 0e4962c43..deb434975 100644
--- a/core/log.class.inc.php
+++ b/core/log.class.inc.php
@@ -691,7 +691,7 @@ abstract class LogAPI
 		static::$m_oMockMetaModelConfig = $oMetaModelConfig;
 	}
 
-	public static function Exception(string $sMessage, throwable $oException, string $sChannel = null, array $aContext = []): void
+	public static function Exception(string $sMessage, throwable $oException, ?string $sChannel = null, array $aContext = []): void
 	{
 		$aErrorLogs = [];
 		$aErrorLogs[] = static::PrepareErrorLog($sMessage, $oException, $aContext);
diff --git a/setup/modulediscovery/ModuleFileReaderException.php b/setup/modulediscovery/ModuleFileReaderException.php
index 64fef5e7f..50b22c393 100644
--- a/setup/modulediscovery/ModuleFileReaderException.php
+++ b/setup/modulediscovery/ModuleFileReaderException.php
@@ -14,7 +14,7 @@ class ModuleFileReaderException extends Exception
 	 * @param int $iHttpCode
 	 * @param Exception|null $oPrevious
 	 */
-	public function __construct($sMessage, $iHttpCode = 0, Exception $oPrevious = null, $sModuleFile = null)
+	public function __construct($sMessage, $iHttpCode = 0, ?Exception $oPrevious = null, $sModuleFile = null)
 	{
 		$e = new Exception("");
 
diff --git a/sources/Application/TwigBase/Controller/Controller.php b/sources/Application/TwigBase/Controller/Controller.php
index c562283d7..7c8d87c46 100644
--- a/sources/Application/TwigBase/Controller/Controller.php
+++ b/sources/Application/TwigBase/Controller/Controller.php
@@ -738,7 +738,7 @@ abstract class Controller extends AbstractController
 	 *
 	 * @param string $sCode Code of the tab
 	 */
-	public function AddAjaxTab(string $sCode, string $sURL, bool $bCache = true, string $sLabel = null): void
+	public function AddAjaxTab(string $sCode, string $sURL, bool $bCache = true, ?string $sLabel = null): void
 	{
 		if (is_null($sLabel)) {
 			$sLabel = Dict::S($sCode);
diff --git a/sources/Application/UI/Base/Component/TurboForm/TurboForm.php b/sources/Application/UI/Base/Component/TurboForm/TurboForm.php
index 2b7bb563e..d09056508 100644
--- a/sources/Application/UI/Base/Component/TurboForm/TurboForm.php
+++ b/sources/Application/UI/Base/Component/TurboForm/TurboForm.php
@@ -22,7 +22,7 @@ class TurboForm extends UIContentBlock
 	protected ?string $sAction;
 	private FormView $oFormView;
 
-	public function __construct(FormView $oFormView, string $sId = null)
+	public function __construct(FormView $oFormView, ?string $sId = null)
 	{
 		parent::__construct($sId);
 		$this->oFormView = $oFormView;
diff --git a/sources/Application/UI/Base/Component/TurboForm/TurboFormUIBlockFactory.php b/sources/Application/UI/Base/Component/TurboForm/TurboFormUIBlockFactory.php
index 414d28b0c..b5cb49072 100644
--- a/sources/Application/UI/Base/Component/TurboForm/TurboFormUIBlockFactory.php
+++ b/sources/Application/UI/Base/Component/TurboForm/TurboFormUIBlockFactory.php
@@ -36,7 +36,7 @@ class TurboFormUIBlockFactory extends AbstractUIBlockFactory
 	 *
 	 * @return \Combodo\iTop\Application\UI\Base\Component\TurboForm\TurboForm An HTML form in which you can add UIBlocks
 	 */
-	public static function MakeStandard(FormView $oFormView, string $sAction = null, string $sId = null): TurboForm
+	public static function MakeStandard(FormView $oFormView, ?string $sAction = null, ?string $sId = null): TurboForm
 	{
 		$oTurboForm = new TurboForm($oFormView, $sId);
 		if (!is_null($sAction)) {
@@ -57,7 +57,7 @@ class TurboFormUIBlockFactory extends AbstractUIBlockFactory
 	 * @return \Combodo\iTop\Application\UI\Base\Component\TurboForm\TurboForm
 	 * @throws \Combodo\iTop\Forms\Block\FormBlockException
 	 */
-	public static function MakeForDashletConfiguration(string $sDashletId, array $aData = [], string $sId = null): TurboForm
+	public static function MakeForDashletConfiguration(string $sDashletId, array $aData = [], ?string $sId = null): TurboForm
 	{
 		$oBlockForm = FormBlockService::GetInstance()->GetFormBlockById($sDashletId, 'Dashlet');
 		$oController = new FormsController();
diff --git a/sources/Application/UI/Base/Component/TurboStream/TurboStream.php b/sources/Application/UI/Base/Component/TurboStream/TurboStream.php
index 877c080b5..5a7a310e9 100644
--- a/sources/Application/UI/Base/Component/TurboStream/TurboStream.php
+++ b/sources/Application/UI/Base/Component/TurboStream/TurboStream.php
@@ -16,7 +16,7 @@ class TurboStream extends UIContentBlock
 	private string $sTarget;
 	private string $sAction;
 
-	public function __construct(string $sTarget, string $sAction, string $sId = null)
+	public function __construct(string $sTarget, string $sAction, ?string $sId = null)
 	{
 		parent::__construct($sId);
 		$this->sTarget = $sTarget;
diff --git a/sources/Application/UI/Base/Component/TurboStream/TurboStreamUIBlockFactory.php b/sources/Application/UI/Base/Component/TurboStream/TurboStreamUIBlockFactory.php
index 84f86b68d..fa8c76fb9 100644
--- a/sources/Application/UI/Base/Component/TurboStream/TurboStreamUIBlockFactory.php
+++ b/sources/Application/UI/Base/Component/TurboStream/TurboStreamUIBlockFactory.php
@@ -31,7 +31,7 @@ class TurboStreamUIBlockFactory extends AbstractUIBlockFactory
 	 *
 	 * @return \Combodo\iTop\Application\UI\Base\Component\TurboUpdate\TurboStream An HTML form in which you can add UIBlocks
 	 */
-	public static function MakeUpdate(string $sTarget, string $sId = null): TurboStream
+	public static function MakeUpdate(string $sTarget, ?string $sId = null): TurboStream
 	{
 		return new TurboStream($sTarget, 'update', $sId);
 	}
@@ -44,7 +44,7 @@ class TurboStreamUIBlockFactory extends AbstractUIBlockFactory
 	 *
 	 * @return \Combodo\iTop\Application\UI\Base\Component\TurboUpdate\TurboStream An HTML form in which you can add UIBlocks
 	 */
-	public static function MakeReplace(string $sTarget, string $sId = null): TurboStream
+	public static function MakeReplace(string $sTarget, ?string $sId = null): TurboStream
 	{
 		return new TurboStream($sTarget, 'replace', $sId);
 	}
@@ -57,7 +57,7 @@ class TurboStreamUIBlockFactory extends AbstractUIBlockFactory
 	 *
 	 * @return \Combodo\iTop\Application\UI\Base\Component\TurboUpdate\TurboStream An HTML form in which you can add UIBlocks
 	 */
-	public static function MakePrepend(string $sTarget, string $sId = null): TurboStream
+	public static function MakePrepend(string $sTarget, ?string $sId = null): TurboStream
 	{
 		return new TurboStream($sTarget, 'prepend', $sId);
 	}
@@ -70,7 +70,7 @@ class TurboStreamUIBlockFactory extends AbstractUIBlockFactory
 	 *
 	 * @return \Combodo\iTop\Application\UI\Base\Component\TurboUpdate\TurboStream An HTML form in which you can add UIBlocks
 	 */
-	public static function MakeAppend(string $sTarget, string $sId = null): TurboStream
+	public static function MakeAppend(string $sTarget, ?string $sId = null): TurboStream
 	{
 		return new TurboStream($sTarget, 'append', $sId);
 	}
diff --git a/sources/Application/WebPage/ErrorPage.php b/sources/Application/WebPage/ErrorPage.php
index 0fec50b95..fd902cbc4 100644
--- a/sources/Application/WebPage/ErrorPage.php
+++ b/sources/Application/WebPage/ErrorPage.php
@@ -51,7 +51,7 @@ class ErrorPage extends NiceWebPage
 		$this->log_warning($sText);
 	}
 
-	public function error($sText, \Throwable $oException = null)
+	public function error($sText, ?\Throwable $oException = null)
 	{
 		$this->add("<div class=\"message message-error\">$sText</div>");
 		if (utils::IsEasterEggAllowed()) {
diff --git a/sources/Core/AttributeDefinition/AttributeBlob.php b/sources/Core/AttributeDefinition/AttributeBlob.php
index e3bc2bb2f..e8c97d394 100644
--- a/sources/Core/AttributeDefinition/AttributeBlob.php
+++ b/sources/Core/AttributeDefinition/AttributeBlob.php
@@ -67,12 +67,12 @@ class AttributeBlob extends AttributeDefinition
 		return true;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return new ormDocument('', '', '');
 	}
 
-	public function IsNullAllowed(DBObject $oHostObject = null)
+	public function IsNullAllowed(?DBObject $oHostObject = null)
 	{
 		return $this->GetOptional("is_null_allowed", false);
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeCaseLog.php b/sources/Core/AttributeDefinition/AttributeCaseLog.php
index f812d656c..9dadebba5 100644
--- a/sources/Core/AttributeDefinition/AttributeCaseLog.php
+++ b/sources/Core/AttributeDefinition/AttributeCaseLog.php
@@ -121,7 +121,7 @@ class AttributeCaseLog extends AttributeLongText
 		}
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return new ormCaseLog();
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeClass.php b/sources/Core/AttributeDefinition/AttributeClass.php
index b9fd7fb51..93b127044 100644
--- a/sources/Core/AttributeDefinition/AttributeClass.php
+++ b/sources/Core/AttributeDefinition/AttributeClass.php
@@ -32,7 +32,7 @@ class AttributeClass extends AttributeString
 		parent::__construct($sCode, $aParams);
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		$sDefault = parent::GetDefaultValue($oHostObject);
 		if (!$this->IsNullAllowed() && $this->IsNull($sDefault)) {
diff --git a/sources/Core/AttributeDefinition/AttributeCustomFields.php b/sources/Core/AttributeDefinition/AttributeCustomFields.php
index bdd75746c..6b173d0eb 100644
--- a/sources/Core/AttributeDefinition/AttributeCustomFields.php
+++ b/sources/Core/AttributeDefinition/AttributeCustomFields.php
@@ -61,7 +61,7 @@ class AttributeCustomFields extends AttributeDefinition
 		return false;
 	} // See ReadValue...
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return new ormCustomFieldsValue($oHostObject, $this->GetCode());
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeDBField.php b/sources/Core/AttributeDefinition/AttributeDBField.php
index 23b27b184..81d79b29c 100644
--- a/sources/Core/AttributeDefinition/AttributeDBField.php
+++ b/sources/Core/AttributeDefinition/AttributeDBField.php
@@ -21,7 +21,7 @@ class AttributeDBField extends AttributeDBFieldVoid
 		return array_merge(parent::ListExpectedParams(), ["default_value", "is_null_allowed"]);
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return $this->MakeRealValue($this->Get("default_value"), $oHostObject);
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeDBFieldVoid.php b/sources/Core/AttributeDefinition/AttributeDBFieldVoid.php
index 5ebac10d0..4a7f08767 100644
--- a/sources/Core/AttributeDefinition/AttributeDBFieldVoid.php
+++ b/sources/Core/AttributeDefinition/AttributeDBFieldVoid.php
@@ -83,7 +83,7 @@ class AttributeDBFieldVoid extends AttributeDefinition
 		return $this->Get("sql");
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return $this->MakeRealValue("", $oHostObject);
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeDashboard.php b/sources/Core/AttributeDefinition/AttributeDashboard.php
index b00d9277f..2918a4c91 100644
--- a/sources/Core/AttributeDefinition/AttributeDashboard.php
+++ b/sources/Core/AttributeDefinition/AttributeDashboard.php
@@ -63,7 +63,7 @@ class AttributeDashboard extends AttributeDefinition
 		return "";
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return null;
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeDateTime.php b/sources/Core/AttributeDefinition/AttributeDateTime.php
index 535ee854f..82bde38e3 100644
--- a/sources/Core/AttributeDefinition/AttributeDateTime.php
+++ b/sources/Core/AttributeDefinition/AttributeDateTime.php
@@ -244,7 +244,7 @@ class AttributeDateTime extends AttributeDBField
 		return $iUnixSeconds;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		$sDefaultValue = $this->Get('default_value');
 		if (utils::IsNotNullOrEmptyString($sDefaultValue)) {
diff --git a/sources/Core/AttributeDefinition/AttributeDefinition.php b/sources/Core/AttributeDefinition/AttributeDefinition.php
index 76ca7234a..0d4699637 100644
--- a/sources/Core/AttributeDefinition/AttributeDefinition.php
+++ b/sources/Core/AttributeDefinition/AttributeDefinition.php
@@ -875,7 +875,7 @@ abstract class AttributeDefinition
 		return null;
 	}
 
-	abstract public function GetDefaultValue(DBObject $oHostObject = null);
+	abstract public function GetDefaultValue(?DBObject $oHostObject = null);
 
 	//
 	// To be overloaded in subclasses
diff --git a/sources/Core/AttributeDefinition/AttributeExternalField.php b/sources/Core/AttributeDefinition/AttributeExternalField.php
index ae6f2e158..bcdfaff7d 100644
--- a/sources/Core/AttributeDefinition/AttributeExternalField.php
+++ b/sources/Core/AttributeDefinition/AttributeExternalField.php
@@ -326,7 +326,7 @@ class AttributeExternalField extends AttributeDefinition
 		return $oExtAttDef->GetSQLExpr();
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		$oExtAttDef = $this->GetExtAttDef();
 
diff --git a/sources/Core/AttributeDefinition/AttributeExternalKey.php b/sources/Core/AttributeDefinition/AttributeExternalKey.php
index 10783fffb..77c47bb8d 100644
--- a/sources/Core/AttributeDefinition/AttributeExternalKey.php
+++ b/sources/Core/AttributeDefinition/AttributeExternalKey.php
@@ -112,7 +112,7 @@ class AttributeExternalKey extends AttributeDBFieldVoid
 		return $this->GetOptional('display_style', 'select');
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return 0;
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeFinalClass.php b/sources/Core/AttributeDefinition/AttributeFinalClass.php
index 281db08f3..0a0c37f54 100644
--- a/sources/Core/AttributeDefinition/AttributeFinalClass.php
+++ b/sources/Core/AttributeDefinition/AttributeFinalClass.php
@@ -50,7 +50,7 @@ class AttributeFinalClass extends AttributeString
 		$this->m_sValue = $sValue;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return $this->m_sValue;
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeFriendlyName.php b/sources/Core/AttributeDefinition/AttributeFriendlyName.php
index de813f54a..dd24db428 100644
--- a/sources/Core/AttributeDefinition/AttributeFriendlyName.php
+++ b/sources/Core/AttributeDefinition/AttributeFriendlyName.php
@@ -133,7 +133,7 @@ class AttributeFriendlyName extends AttributeDefinition
 		$this->m_sValue = $sValue;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return $this->m_sValue;
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeImage.php b/sources/Core/AttributeDefinition/AttributeImage.php
index f5e0f97a1..37e2c429b 100644
--- a/sources/Core/AttributeDefinition/AttributeImage.php
+++ b/sources/Core/AttributeDefinition/AttributeImage.php
@@ -74,7 +74,7 @@ class AttributeImage extends AttributeBlob
 		return $oDoc;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return new ormDocument('', '', '');
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeLinkedSet.php b/sources/Core/AttributeDefinition/AttributeLinkedSet.php
index 840c9eaea..e0b99b5a1 100644
--- a/sources/Core/AttributeDefinition/AttributeLinkedSet.php
+++ b/sources/Core/AttributeDefinition/AttributeLinkedSet.php
@@ -122,7 +122,7 @@ class AttributeLinkedSet extends AttributeDefinition
 	 * @throws CoreException
 	 * @throws CoreWarning
 	 */
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		if ($oHostObject === null) {
 			return null;
diff --git a/sources/Core/AttributeDefinition/AttributeObjectKey.php b/sources/Core/AttributeDefinition/AttributeObjectKey.php
index 4c7643f01..122c48909 100644
--- a/sources/Core/AttributeDefinition/AttributeObjectKey.php
+++ b/sources/Core/AttributeDefinition/AttributeObjectKey.php
@@ -52,7 +52,7 @@ class AttributeObjectKey extends AttributeDBFieldVoid
 		return "INT(11)".($bFullSpec ? " DEFAULT 0" : "");
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return 0;
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeObsolescenceFlag.php b/sources/Core/AttributeDefinition/AttributeObsolescenceFlag.php
index 8cea14cd6..d976bdd73 100644
--- a/sources/Core/AttributeDefinition/AttributeObsolescenceFlag.php
+++ b/sources/Core/AttributeDefinition/AttributeObsolescenceFlag.php
@@ -109,7 +109,7 @@ class AttributeObsolescenceFlag extends AttributeBoolean
 		return null;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return $this->MakeRealValue(false, $oHostObject);
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeOneWayPassword.php b/sources/Core/AttributeDefinition/AttributeOneWayPassword.php
index 288404b77..38e72d716 100644
--- a/sources/Core/AttributeDefinition/AttributeOneWayPassword.php
+++ b/sources/Core/AttributeDefinition/AttributeOneWayPassword.php
@@ -64,7 +64,7 @@ class AttributeOneWayPassword extends AttributeDefinition implements iAttributeN
 		return true;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return "";
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeRedundancySettings.php b/sources/Core/AttributeDefinition/AttributeRedundancySettings.php
index 7778d7b2d..49d8420fc 100644
--- a/sources/Core/AttributeDefinition/AttributeRedundancySettings.php
+++ b/sources/Core/AttributeDefinition/AttributeRedundancySettings.php
@@ -93,7 +93,7 @@ class AttributeRedundancySettings extends AttributeDBField
 		return 20;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		$sRet = 'disabled';
 		if ($this->Get('enabled')) {
diff --git a/sources/Core/AttributeDefinition/AttributeSet.php b/sources/Core/AttributeDefinition/AttributeSet.php
index b485c1278..f70e82d73 100644
--- a/sources/Core/AttributeDefinition/AttributeSet.php
+++ b/sources/Core/AttributeDefinition/AttributeSet.php
@@ -131,7 +131,7 @@ abstract class AttributeSet extends AttributeDBFieldVoid
 		return true;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return null;
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeStopWatch.php b/sources/Core/AttributeDefinition/AttributeStopWatch.php
index dfd24141d..9d53ee95c 100644
--- a/sources/Core/AttributeDefinition/AttributeStopWatch.php
+++ b/sources/Core/AttributeDefinition/AttributeStopWatch.php
@@ -72,7 +72,7 @@ class AttributeStopWatch extends AttributeDefinition
 		return true;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return $this->NewStopWatch();
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeSubItem.php b/sources/Core/AttributeDefinition/AttributeSubItem.php
index fa0f18d08..2f9e5f63a 100644
--- a/sources/Core/AttributeDefinition/AttributeSubItem.php
+++ b/sources/Core/AttributeDefinition/AttributeSubItem.php
@@ -117,7 +117,7 @@ class AttributeSubItem extends AttributeDefinition
 		return false;
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		return null;
 	}
diff --git a/sources/Core/AttributeDefinition/AttributeTagSet.php b/sources/Core/AttributeDefinition/AttributeTagSet.php
index b547f17c3..1e4ed3c5f 100644
--- a/sources/Core/AttributeDefinition/AttributeTagSet.php
+++ b/sources/Core/AttributeDefinition/AttributeTagSet.php
@@ -276,7 +276,7 @@ class AttributeTagSet extends AttributeSet
 		return new ormTagSet(MetaModel::GetAttributeOrigin($this->GetHostClass(), $this->GetCode()), $this->GetCode(), $this->GetMaxItems());
 	}
 
-	public function GetDefaultValue(DBObject $oHostObject = null)
+	public function GetDefaultValue(?DBObject $oHostObject = null)
 	{
 		$oTagSet = new ormTagSet(MetaModel::GetAttributeOrigin($this->GetHostClass(), $this->GetCode()), $this->GetCode(), $this->GetMaxItems());
 		$oTagSet->SetValues([]);
diff --git a/sources/Forms/Block/AbstractFormBlock.php b/sources/Forms/Block/AbstractFormBlock.php
index 67ecfd9a3..68fbbc7e0 100644
--- a/sources/Forms/Block/AbstractFormBlock.php
+++ b/sources/Forms/Block/AbstractFormBlock.php
@@ -253,7 +253,7 @@ abstract class AbstractFormBlock implements IFormBlock
 	 * @throws FormBlockIOException
 	 * @throws RegisterException
 	 */
-	public function AddOutput(string $sName, string $sType, bool $bIsArray = false, AbstractConverter $oConverter = null): AbstractFormBlock
+	public function AddOutput(string $sName, string $sType, bool $bIsArray = false, ?AbstractConverter $oConverter = null): AbstractFormBlock
 	{
 		$this->oIORegister->AddOutput($sName, $sType, $bIsArray, $oConverter);
 		return $this;
@@ -413,7 +413,7 @@ abstract class AbstractFormBlock implements IFormBlock
 	 *
 	 * @return bool
 	 */
-	public function IsInputsDataReady(string $sType = null): bool
+	public function IsInputsDataReady(?string $sType = null): bool
 	{
 		return $this->oIORegister->IsInputsDataReady($sType);
 	}
diff --git a/sources/Forms/Block/AbstractTypeFormBlock.php b/sources/Forms/Block/AbstractTypeFormBlock.php
index 9e85e3686..31ce6a66c 100644
--- a/sources/Forms/Block/AbstractTypeFormBlock.php
+++ b/sources/Forms/Block/AbstractTypeFormBlock.php
@@ -53,7 +53,7 @@ abstract class AbstractTypeFormBlock extends AbstractFormBlock
 	 * @return bool
 	 * @throws FormBlockException
 	 */
-	public function IsVisible(string $sEventType = null): bool
+	public function IsVisible(?string $sEventType = null): bool
 	{
 		$oInput = $this->GetInput(self::INPUT_VISIBLE);
 		if (!$oInput->IsBound()) {
@@ -68,7 +68,7 @@ abstract class AbstractTypeFormBlock extends AbstractFormBlock
 	/**
 	 * @return true
 	 */
-	public function AllowAdd(string $sEventType = null): bool
+	public function AllowAdd(?string $sEventType = null): bool
 	{
 		return true;
 	}
diff --git a/sources/Forms/Block/FormBlockService.php b/sources/Forms/Block/FormBlockService.php
index 0e7430b7b..1c80605ec 100644
--- a/sources/Forms/Block/FormBlockService.php
+++ b/sources/Forms/Block/FormBlockService.php
@@ -20,12 +20,12 @@ class FormBlockService
 {
 	private static FormBlockService $oInstance;
 
-	protected function __construct(ModelReflection $oModelReflection = null)
+	protected function __construct(?ModelReflection $oModelReflection = null)
 	{
 		ServiceLocator::GetInstance()->RegisterService('ModelReflection', $oModelReflection ?? new ModelReflectionRuntime());
 	}
 
-	final public static function GetInstance(ModelReflection $oModelReflection = null): FormBlockService
+	final public static function GetInstance(?ModelReflection $oModelReflection = null): FormBlockService
 	{
 		if (!isset(static::$oInstance)) {
 			static::$oInstance = new FormBlockService($oModelReflection);
diff --git a/sources/Forms/FormBuilder/DependencyHandler.php b/sources/Forms/FormBuilder/DependencyHandler.php
index 92a16601f..0a3bb6fc4 100644
--- a/sources/Forms/FormBuilder/DependencyHandler.php
+++ b/sources/Forms/FormBuilder/DependencyHandler.php
@@ -161,7 +161,7 @@ class DependencyHandler
 	 * @return void
 	 * @throws FormBlockException
 	 */
-	private function CheckDependencies(FormInterface|FormBuilderInterface $oForm, string $sOutputBlock = null, string $sEventType = null): void
+	private function CheckDependencies(FormInterface|FormBuilderInterface $oForm, ?string $sOutputBlock = null, ?string $sEventType = null): void
 	{
 		$aImpactedBlocks = $this->aDependentBlocks;
 		if ($sOutputBlock !== null) {
diff --git a/sources/Forms/FormBuilder/DependencyMap.php b/sources/Forms/FormBuilder/DependencyMap.php
index 836c856f8..4503b593c 100644
--- a/sources/Forms/FormBuilder/DependencyMap.php
+++ b/sources/Forms/FormBuilder/DependencyMap.php
@@ -171,7 +171,7 @@ class DependencyMap
 	 *
 	 * @return array|null
 	 */
-	public function GetBlocksImpactedBy(string $sBlockName, callable $oFilter = null): ?array
+	public function GetBlocksImpactedBy(string $sBlockName, ?callable $oFilter = null): ?array
 	{
 		if (!array_key_exists($sBlockName, $this->aBlocksImpactedBy)) {
 			return null;
diff --git a/sources/Forms/IO/AbstractFormIO.php b/sources/Forms/IO/AbstractFormIO.php
index 49d50ae46..4a5ecdc58 100644
--- a/sources/Forms/IO/AbstractFormIO.php
+++ b/sources/Forms/IO/AbstractFormIO.php
@@ -164,7 +164,7 @@ class AbstractFormIO
 	 *
 	 * @return mixed
 	 */
-	public function GetValue(string $sEventType = null): mixed
+	public function GetValue(?string $sEventType = null): mixed
 	{
 		if ($sEventType === null) {
 			return $this->Value();
@@ -190,7 +190,7 @@ class AbstractFormIO
 	 *
 	 * @return bool
 	 */
-	public function HasEventValue(string $sEventType = null): bool
+	public function HasEventValue(?string $sEventType = null): bool
 	{
 		if ($sEventType === null) {
 			return $this->HasValue();
diff --git a/sources/Forms/IO/FormInput.php b/sources/Forms/IO/FormInput.php
index 4bdbe0023..ac05839cf 100644
--- a/sources/Forms/IO/FormInput.php
+++ b/sources/Forms/IO/FormInput.php
@@ -28,7 +28,7 @@ class FormInput extends AbstractFormIO
 	 *
 	 * @return bool
 	 */
-	public function IsEventDataReady(string $sEventType = null): bool
+	public function IsEventDataReady(?string $sEventType = null): bool
 	{
 		return $this->HasEventValue($sEventType);
 	}
diff --git a/sources/Forms/IO/FormOutput.php b/sources/Forms/IO/FormOutput.php
index 361ec6929..d8a799772 100644
--- a/sources/Forms/IO/FormOutput.php
+++ b/sources/Forms/IO/FormOutput.php
@@ -34,7 +34,7 @@ class FormOutput extends AbstractFormIO
 	 *
 	 * @throws FormBlockIOException
 	 */
-	public function __construct(string $sName, string $sType, bool $bIsArray = false, AbstractConverter $oConverter = null)
+	public function __construct(string $sName, string $sType, bool $bIsArray = false, ?AbstractConverter $oConverter = null)
 	{
 		parent::__construct($sName, $sType, $bIsArray);
 		$this->oConverter = $oConverter;
diff --git a/sources/Forms/Register/IORegister.php b/sources/Forms/Register/IORegister.php
index 4d434ddbc..8caab57cf 100644
--- a/sources/Forms/Register/IORegister.php
+++ b/sources/Forms/Register/IORegister.php
@@ -135,7 +135,7 @@ class IORegister
 	 * @throws FormBlockIOException
 	 * @throws RegisterException
 	 */
-	public function AddOutput(string $sName, string $sType, bool $bIsArray = false, AbstractConverter $oConverter = null): void
+	public function AddOutput(string $sName, string $sType, bool $bIsArray = false, ?AbstractConverter $oConverter = null): void
 	{
 		$oFormOutput = new FormOutput($sName, $sType, $bIsArray, $oConverter);
 		$oFormOutput->SetOwnerBlock($this->oFormBlock);
@@ -349,7 +349,7 @@ class IORegister
 	 *
 	 * @return bool
 	 */
-	public function IsInputsDataReady(string $sType = null): bool
+	public function IsInputsDataReady(?string $sType = null): bool
 	{
 		foreach ($this->aInputs as $oFormInput) {
 			if ($oFormInput->IsBound()) {
diff --git a/sources/Forms/Validator/AttributeExist.php b/sources/Forms/Validator/AttributeExist.php
index 001f94baf..07f7cbfa8 100644
--- a/sources/Forms/Validator/AttributeExist.php
+++ b/sources/Forms/Validator/AttributeExist.php
@@ -38,7 +38,7 @@ class AttributeExist extends Constraint
 	 * @param array|null $aGroups
 	 * @param mixed|null $oPayload
 	 */
-	public function __construct(string $sOqlPropertyPath = null, string $sFilter = null, array $aOptions = [], ?array $aGroups = null, mixed $oPayload = null)
+	public function __construct(?string $sOqlPropertyPath = null, ?string $sFilter = null, array $aOptions = [], ?array $aGroups = null, mixed $oPayload = null)
 	{
 		if ($sOqlPropertyPath === null) {
 			throw new InvalidArgumentException('The argument "sOqlPropertyPath" must be set.');
diff --git a/sources/PropertyType/PropertyTypeDesign.php b/sources/PropertyType/PropertyTypeDesign.php
index 1b67b88a3..ac9d533b5 100644
--- a/sources/PropertyType/PropertyTypeDesign.php
+++ b/sources/PropertyType/PropertyTypeDesign.php
@@ -18,7 +18,7 @@ use utils;
  */
 class PropertyTypeDesign extends DesignDocument
 {
-	public function __construct(string $sDesignSourceId = null, string $sType = 'Default')
+	public function __construct(?string $sDesignSourceId = null, string $sType = 'Default')
 	{
 		parent::__construct();