diff --git a/apps/oauth2/lib/Migration/Version011901Date20240829164356.php b/apps/oauth2/lib/Migration/Version011901Date20240829164356.php
index 9ce9ff371cbde..20f5754bf1138 100644
--- a/apps/oauth2/lib/Migration/Version011901Date20240829164356.php
+++ b/apps/oauth2/lib/Migration/Version011901Date20240829164356.php
@@ -23,7 +23,7 @@ public function __construct(
 	) {
 	}
 
-	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options) {
+	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
 		$qbUpdate = $this->connection->getQueryBuilder();
 		$qbUpdate->update('oauth2_clients')
 			->set('secret', $qbUpdate->createParameter('updateSecret'))
diff --git a/apps/oauth2/tests/Controller/OauthApiControllerTest.php b/apps/oauth2/tests/Controller/OauthApiControllerTest.php
index f3ffbfe799105..e1864b9612ad5 100644
--- a/apps/oauth2/tests/Controller/OauthApiControllerTest.php
+++ b/apps/oauth2/tests/Controller/OauthApiControllerTest.php
@@ -278,7 +278,7 @@ public function testRefreshTokenInvalidClient($clientId, $clientSecret) {
 
 		$client = new Client();
 		$client->setClientIdentifier('clientId');
-		$client->setSecret('hashedClientSecret');
+		$client->setSecret(bin2hex('hashedClientSecret'));
 		$this->clientMapper->method('getByUid')
 			->with(42)
 			->willReturn($client);
@@ -303,7 +303,7 @@ public function testRefreshTokenInvalidAppToken() {
 
 		$client = new Client();
 		$client->setClientIdentifier('clientId');
-		$client->setSecret('hashedClientSecret');
+		$client->setSecret(bin2hex('hashedClientSecret'));
 		$this->clientMapper->method('getByUid')
 			->with(42)
 			->willReturn($client);
@@ -341,7 +341,7 @@ public function testRefreshTokenValidAppToken() {
 
 		$client = new Client();
 		$client->setClientIdentifier('clientId');
-		$client->setSecret('hashedClientSecret');
+		$client->setSecret(bin2hex('hashedClientSecret'));
 		$this->clientMapper->method('getByUid')
 			->with(42)
 			->willReturn($client);
@@ -437,7 +437,7 @@ public function testRefreshTokenValidAppTokenBasicAuth() {
 
 		$client = new Client();
 		$client->setClientIdentifier('clientId');
-		$client->setSecret('hashedClientSecret');
+		$client->setSecret(bin2hex('hashedClientSecret'));
 		$this->clientMapper->method('getByUid')
 			->with(42)
 			->willReturn($client);
@@ -536,7 +536,7 @@ public function testRefreshTokenExpiredAppToken() {
 
 		$client = new Client();
 		$client->setClientIdentifier('clientId');
-		$client->setSecret('hashedClientSecret');
+		$client->setSecret(bin2hex('hashedClientSecret'));
 		$this->clientMapper->method('getByUid')
 			->with(42)
 			->willReturn($client);
diff --git a/apps/oauth2/tests/Controller/SettingsControllerTest.php b/apps/oauth2/tests/Controller/SettingsControllerTest.php
index 191ee8de53b09..39948595cbf59 100644
--- a/apps/oauth2/tests/Controller/SettingsControllerTest.php
+++ b/apps/oauth2/tests/Controller/SettingsControllerTest.php
@@ -109,7 +109,7 @@ public function testAddClient() {
 		$client = new Client();
 		$client->setName('My Client Name');
 		$client->setRedirectUri('https://example.com/');
-		$client->setSecret('MyHashedSecret');
+		$client->setSecret(bin2hex('MyHashedSecret'));
 		$client->setClientIdentifier('MyClientIdentifier');
 
 		$this->clientMapper
@@ -118,7 +118,7 @@ public function testAddClient() {
 			->with($this->callback(function (Client $c) {
 				return $c->getName() === 'My Client Name' &&
 					$c->getRedirectUri() === 'https://example.com/' &&
-					$c->getSecret() === 'MyHashedSecret' &&
+					$c->getSecret() === bin2hex('MyHashedSecret') &&
 					$c->getClientIdentifier() === 'MyClientIdentifier';
 			}))->willReturnCallback(function (Client $c) {
 				$c->setId(42);
@@ -161,7 +161,7 @@ public function testDeleteClient() {
 		$client->setId(123);
 		$client->setName('My Client Name');
 		$client->setRedirectUri('https://example.com/');
-		$client->setSecret('MyHashedSecret');
+		$client->setSecret(bin2hex('MyHashedSecret'));
 		$client->setClientIdentifier('MyClientIdentifier');
 
 		$this->clientMapper