diff --git a/.make/build/afterBuild.php b/.make/build/afterBuild.php
index cecdaf9e9..e1ab17a1f 100644
--- a/.make/build/afterBuild.php
+++ b/.make/build/afterBuild.php
@@ -22,13 +22,13 @@ $iElapsed = time() - $iBeginTime;
 
 if (count($aFailedCommands))
 {
-	fwrite(STDERR, "\nafterBuild execution failed! (in ${iElapsed}s)\n");
+	fwrite(STDERR, "\nafterBuild execution failed! (in {$iElapsed}s)\n");
 	fwrite(STDERR, "List of failling commands:\n - " . implode("\n - ", $aFailedCommands) . "\n");
 	exit(1);
 }
 
 
-echo "\nDone (${iElapsed}s)\n";
+echo "\nDone ({$iElapsed}s)\n";
 exit(0);
 
 /**
@@ -74,7 +74,7 @@ function ExecCommand($cmd) {
 	}
 	else
 	{
-		echo "| elapsed:${iElapsed}s \n";
+		echo "| elapsed:{$iElapsed}s \n";
 	}
 
 	if (!empty($stderr))
diff --git a/application/loginwebpage.class.inc.php b/application/loginwebpage.class.inc.php
index 33827e493..a7ecd12fb 100644
--- a/application/loginwebpage.class.inc.php
+++ b/application/loginwebpage.class.inc.php
@@ -910,13 +910,13 @@ class LoginWebPage extends NiceWebPage
 			$aAllProfiles = array();
 			while ($oProfile = $oProfilesSet->Fetch())
 			{
-				$aAllProfiles[strtolower($oProfile->GetName())] = $oProfile->GetKey();
+				$aAllProfiles[mb_strtolower($oProfile->GetName())] = $oProfile->GetKey();
 			}
 
 			$aProfiles = array();
 			foreach ($aRequestedProfiles as $sRequestedProfile)
 			{
-				$sRequestedProfile = strtolower($sRequestedProfile);
+				$sRequestedProfile = mb_strtolower($sRequestedProfile);
 				if (isset($aAllProfiles[$sRequestedProfile]))
 				{
 					$aProfiles[] = $aAllProfiles[$sRequestedProfile];
diff --git a/core/MyHelpers.class.inc.php b/core/MyHelpers.class.inc.php
index ece53ea7e..32aea4c26 100644
--- a/core/MyHelpers.class.inc.php
+++ b/core/MyHelpers.class.inc.php
@@ -521,6 +521,6 @@ class Str
 
 	public static function islowcase($sString)
 	{
-		return (strtolower($sString) == $sString);
+		return (mb_strtolower($sString) == $sString);
 	}
 }
diff --git a/core/action.class.inc.php b/core/action.class.inc.php
index eea2d6f52..4777a0925 100644
--- a/core/action.class.inc.php
+++ b/core/action.class.inc.php
@@ -677,10 +677,11 @@ class ActionEmail extends ActionNotification
 		if (isset($aContextArgs['attachments']))
 		{
 			$aAttachmentReport = array();
+			/** @var \ormDocument $oDocument */
 			foreach($aContextArgs['attachments'] as $oDocument)
 			{
 				$aMessageContent['attachments'][] = ['data' => $oDocument->GetData(), 'filename' => $oDocument->GetFileName(), 'mime_type' => $oDocument->GetMimeType()];
-				$aAttachmentReport[] = array($oDocument->GetFileName(), $oDocument->GetMimeType(), strlen($oDocument->GetData()));
+				$aAttachmentReport[] = array($oDocument->GetFileName(), $oDocument->GetMimeType(), strlen($oDocument->GetData() ?? ''));
 			}
 			$oLog->Set('attachments', $aAttachmentReport);
 		}
diff --git a/core/attributedef.class.inc.php b/core/attributedef.class.inc.php
index 764dae3ab..e83a07f6b 100644
--- a/core/attributedef.class.inc.php
+++ b/core/attributedef.class.inc.php
@@ -3506,7 +3506,7 @@ class AttributeBoolean extends AttributeInteger
 		$sProposedValue, $bLocalizedValue = false, $sSepItem = null, $sSepAttribute = null, $sSepValue = null,
 		$sAttributeQualifier = null
 	) {
-		$sInput = strtolower(trim($sProposedValue));
+		$sInput = mb_strtolower(trim($sProposedValue));
 		if ($bLocalizedValue)
 		{
 			switch ($sInput)
diff --git a/core/designdocument.class.inc.php b/core/designdocument.class.inc.php
index df3dea7bd..59418391a 100644
--- a/core/designdocument.class.inc.php
+++ b/core/designdocument.class.inc.php
@@ -64,16 +64,22 @@ class DesignDocument extends DOMDocument
 	/**
 	 * Overload of the standard API
 	 *
-	 * @param $filename
+	 * @param string $filename
 	 * @param int $options
+	 *
+	 * @return bool
 	 */
-	public function load($filename, $options = null)
+	public function load(string $filename, int $options = 0): bool
 	{
 		libxml_clear_errors();
 		if (parent::load($filename, LIBXML_NOBLANKS) === false) {
 			$aErrors = libxml_get_errors();
 			IssueLog::Error("Error loading $filename", LogAPI::CHANNEL_DEFAULT, $aErrors);
+
+			return false;
 		}
+
+		return true;
 	}
 
 	/**
diff --git a/core/oql/build/PHP/ParserGenerator.php b/core/oql/build/PHP/ParserGenerator.php
index 4a6fa08a4..51cbf3c41 100644
--- a/core/oql/build/PHP/ParserGenerator.php
+++ b/core/oql/build/PHP/ParserGenerator.php
@@ -739,7 +739,7 @@ class PHP_ParserGenerator
             while (isset($errmsg[$restart]) && $errmsg[$restart] == ' ') {
                 $restart++;
             }
-            printf("%s%.${end}s\n", $prefix, $errmsg);
+            printf("%s%.{$end}s\n", $prefix, $errmsg);
             $errmsg = substr($errmsg, $restart);
         }
     }
@@ -771,7 +771,7 @@ class PHP_ParserGenerator
             for ($j = $i; $j < $this->nsymbol; $j += $skip) {
                 $sp = $this->symbols[$j];
                 //assert( sp->index==j );
-                printf(" %3d %-${maxlen}.${maxlen}s", $j, $sp->name);
+                printf(" %3d %-{$maxlen}.{$maxlen}s", $j, $sp->name);
             }
             print "\n";
         }
diff --git a/core/oql/build/PHP/ParserGenerator/Action.php b/core/oql/build/PHP/ParserGenerator/Action.php
index e0108890e..7f87d7740 100644
--- a/core/oql/build/PHP/ParserGenerator/Action.php
+++ b/core/oql/build/PHP/ParserGenerator/Action.php
@@ -231,19 +231,19 @@ class PHP_ParserGenerator_Action
         switch ($this->type)
         {
         case self::SHIFT:
-            fprintf($fp, "%${indent}s shift  %d", $this->sp->name, $this->x->statenum);
+            fprintf($fp, "%{$indent}s shift  %d", $this->sp->name, $this->x->statenum);
             break;
         case self::REDUCE:
-            fprintf($fp, "%${indent}s reduce %d", $this->sp->name, $this->x->index);
+            fprintf($fp, "%{$indent}s reduce %d", $this->sp->name, $this->x->index);
             break;
         case self::ACCEPT:
-            fprintf($fp, "%${indent}s accept", $this->sp->name);
+            fprintf($fp, "%{$indent}s accept", $this->sp->name);
             break;
         case self::ERROR:
-            fprintf($fp, "%${indent}s error", $this->sp->name);
+            fprintf($fp, "%{$indent}s error", $this->sp->name);
             break;
         case self::CONFLICT:
-            fprintf($fp, "%${indent}s reduce %-3d ** Parsing conflict **", $this->sp->name, $this->x->index);
+            fprintf($fp, "%{$indent}s reduce %-3d ** Parsing conflict **", $this->sp->name, $this->x->index);
             break;
         case self::SH_RESOLVED:
         case self::RD_RESOLVED:
diff --git a/datamodels/2.x/authent-cas/src/CASLoginExtension.php b/datamodels/2.x/authent-cas/src/CASLoginExtension.php
index acb6ab60b..1b7c7c288 100644
--- a/datamodels/2.x/authent-cas/src/CASLoginExtension.php
+++ b/datamodels/2.x/authent-cas/src/CASLoginExtension.php
@@ -488,7 +488,7 @@ class CASUserProvisioning
 		$aAllProfiles = array();
 		while($oProfile = $oProfilesSet->Fetch())
 		{
-			$aAllProfiles[strtolower($oProfile->GetName())] = $oProfile->GetKey();
+			$aAllProfiles[mb_strtolower($oProfile->GetName())] = $oProfile->GetKey();
 		}
 
 		// Translate the CAS/LDAP group names into iTop profile names
@@ -498,9 +498,9 @@ class CASUserProvisioning
 		{
 			if (preg_match($sPattern, $sGroupName, $aMatches))
 			{
-				if (array_key_exists(strtolower($aMatches[1]), $aAllProfiles))
+				if (array_key_exists(mb_strtolower($aMatches[1]), $aAllProfiles))
 				{
-					$aProfiles[] = $aAllProfiles[strtolower($aMatches[1])];
+					$aProfiles[] = $aAllProfiles[mb_strtolower($aMatches[1])];
 					phpCAS::log("Info: Adding the profile '{$aMatches[1]}' from CAS.");
 				}
 				else
@@ -522,10 +522,10 @@ class CASUserProvisioning
 			$aCASDefaultProfiles = explode(';', $sCASDefaultProfiles);
 			foreach($aCASDefaultProfiles as $sDefaultProfileName)
 			{
-				if (array_key_exists(strtolower($sDefaultProfileName), $aAllProfiles))
+				if (array_key_exists(mb_strtolower($sDefaultProfileName), $aAllProfiles))
 				{
-					$aProfiles[] = $aAllProfiles[strtolower($sDefaultProfileName)];
-					phpCAS::log("Info: Adding the default profile '".$aAllProfiles[strtolower($sDefaultProfileName)]."' from CAS.");
+					$aProfiles[] = $aAllProfiles[mb_strtolower($sDefaultProfileName)];
+					phpCAS::log("Info: Adding the default profile '".$aAllProfiles[mb_strtolower($sDefaultProfileName)]."' from CAS.");
 				}
 				else
 				{
diff --git a/tests/php-unit-tests/src/BaseTestCase/ItopTestCase.php b/tests/php-unit-tests/src/BaseTestCase/ItopTestCase.php
index 13a6d5dee..a288a404d 100644
--- a/tests/php-unit-tests/src/BaseTestCase/ItopTestCase.php
+++ b/tests/php-unit-tests/src/BaseTestCase/ItopTestCase.php
@@ -345,7 +345,7 @@ abstract class ItopTestCase extends TestCase
 		foreach ($class->getProperties() as $property) {
 			if (!$property->isStatic()) continue;
 			$property->setAccessible(true);
-			$property->setValue(static::$aBackupStaticProperties[$sClass][$property->getName()]);
+			$property->setValue(null, static::$aBackupStaticProperties[$sClass][$property->getName()]);
 		}
 	}
 
@@ -381,7 +381,7 @@ abstract class ItopTestCase extends TestCase
 	public function SetNonPublicStaticProperty(string $sClass, string $sProperty, $value)
 	{
 		$oProperty = $this->GetProperty($sClass, $sProperty);
-		$oProperty->setValue($value);
+		$oProperty->setValue(null, $value);
 	}
 
 	public static function RecurseRmdir($dir)