diff --git a/phpstan.neon b/phpstan.neon
index 4817ce70..79781d51 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -4,7 +4,7 @@ parameters:
         - tests
     parallel:
         maximumNumberOfProcesses: 4
-    level: 6
+    level: 7
     inferPrivatePropertyTypeFromConstructor: true
     bootstrapFiles:
       - tools/bootstrap.php
diff --git a/src/Core/Track.php b/src/Core/Track.php
index da7ba15b..06f2f315 100644
--- a/src/Core/Track.php
+++ b/src/Core/Track.php
@@ -37,7 +37,7 @@
 
     private string $source;
 
-    public function __construct(object $track)
+    public function __construct(\stdClass $track)
     {
         $this->href = $track->href;
         $this->kind = $track->kind;
diff --git a/src/Http/Transport/CurlTransport.php b/src/Http/Transport/CurlTransport.php
index 8da7fb6e..3016e65d 100644
--- a/src/Http/Transport/CurlTransport.php
+++ b/src/Http/Transport/CurlTransport.php
@@ -195,6 +195,8 @@ private static function getHeadersAndContentFromCurlHandle(\CurlHandle $curlHand
         $headers = [];
 
         curl_setopt($curlHandle, \CURLOPT_HEADER, true);
+
+        /** @var string|false $responseContent */
         $responseContent = curl_exec($curlHandle);
 
         // @codeCoverageIgnoreStart
diff --git a/src/Parameters/CreateMeetingParameters.php b/src/Parameters/CreateMeetingParameters.php
index da640590..e42e0b50 100644
--- a/src/Parameters/CreateMeetingParameters.php
+++ b/src/Parameters/CreateMeetingParameters.php
@@ -446,6 +446,10 @@ public function getModules(): string
         // Get xml as string after modules have been added
         $resultXML = $xml->asXML();
 
+        if (false === $resultXML) {
+            throw new \LogicException('Could not generate XML.');
+        }
+
         // If xml was not modified (no modules added), return an empty string
         if ($emptyXML === $resultXML) {
             return '';
@@ -496,7 +500,7 @@ public function getHTTPQuery(): string
         // Pre-defined groups to automatically assign the students to a given breakout room
         if (!empty($this->breakoutRoomsGroups)) {
             $queries = array_merge($queries, [
-                'groups' => json_encode($this->breakoutRoomsGroups),
+                'groups' => json_encode($this->breakoutRoomsGroups, \JSON_THROW_ON_ERROR),
             ]);
         }
 
diff --git a/src/Parameters/InsertDocumentParameters.php b/src/Parameters/InsertDocumentParameters.php
index 8ffad3c8..700fe48e 100644
--- a/src/Parameters/InsertDocumentParameters.php
+++ b/src/Parameters/InsertDocumentParameters.php
@@ -72,7 +72,7 @@ public function removePresentation(string $url): self
         return $this;
     }
 
-    public function getPresentationsAsXML(): string|false
+    public function getPresentationsAsXML(): string
     {
         $result = '';
 
@@ -87,6 +87,10 @@ public function getPresentationsAsXML(): string|false
             $result = $xml->asXML();
         }
 
+        if (false === $result) {
+            throw new \LogicException('Could not generate XML.');
+        }
+
         return $result;
     }
 }
diff --git a/src/Responses/BaseResponseAsJson.php b/src/Responses/BaseResponseAsJson.php
index aff7bebd..cba03793 100644
--- a/src/Responses/BaseResponseAsJson.php
+++ b/src/Responses/BaseResponseAsJson.php
@@ -53,7 +53,7 @@ public function getRawJson(): string|false
      */
     public function getRawArray(): array
     {
-        return json_decode(json_encode($this->data), true);
+        return json_decode(json_encode($this->data, \JSON_THROW_ON_ERROR), true);
     }
 
     public function getMessage(): string
diff --git a/tests/common/TestCase.php b/tests/common/TestCase.php
index 85376e93..1300cb46 100644
--- a/tests/common/TestCase.php
+++ b/tests/common/TestCase.php
@@ -294,12 +294,22 @@ protected function getUpdateRecordingsParamsMock(array $params): UpdateRecording
 
     protected function loadXmlFile(string $path): \SimpleXMLElement
     {
-        return simplexml_load_string(file_get_contents($path));
+        $content = file_get_contents($path);
+        $this->assertIsString($content);
+
+        $xml = simplexml_load_string($content);
+
+        $this->assertNotFalse($xml);
+
+        return $xml;
     }
 
     protected function loadJsonFile(string $path): string
     {
-        return file_get_contents($path);
+        $content = file_get_contents($path);
+        $this->assertIsString($content);
+
+        return $content;
     }
 
     protected function minifyString(string $string): string
diff --git a/tests/functional/AbstractBigBlueButtonFunctionalTest.php b/tests/functional/BigBlueButtonFunctionalTestAbstract.php
similarity index 95%
rename from tests/functional/AbstractBigBlueButtonFunctionalTest.php
rename to tests/functional/BigBlueButtonFunctionalTestAbstract.php
index 074963ff..3b260025 100644
--- a/tests/functional/AbstractBigBlueButtonFunctionalTest.php
+++ b/tests/functional/BigBlueButtonFunctionalTestAbstract.php
@@ -36,7 +36,7 @@
 /**
  * Class BigBlueButtonIntegrationTest.
  */
-abstract class AbstractBigBlueButtonFunctionalTest extends TestCase
+abstract class BigBlueButtonFunctionalTestAbstract extends TestCase
 {
     private BigBlueButton $bbb;
 
@@ -153,7 +153,11 @@ public function testCreateMeetingWithDocumentUrlAndFileName(): void
     public function testCreateMeetingWithDocumentEmbedded(): void
     {
         $params = $this->getCreateMock($this->generateCreateParams());
-        $params->addPresentation('bbb_logo.png', file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'fixtures'.\DIRECTORY_SEPARATOR.'bbb_logo.png'));
+
+        $content = file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'fixtures'.\DIRECTORY_SEPARATOR.'bbb_logo.png');
+        $this->assertIsString($content);
+
+        $params->addPresentation('bbb_logo.png', $content);
 
         $result = $this->bbb->createMeeting($params);
 
@@ -172,7 +176,11 @@ public function testCreateMeetingWithMultiDocument(): void
     {
         $params = $this->getCreateMock($this->generateCreateParams());
         $params->addPresentation('https://picsum.photos/3840/2160/?random', null, 'presentation.png');
-        $params->addPresentation('logo.png', file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'fixtures'.\DIRECTORY_SEPARATOR.'bbb_logo.png'));
+
+        $content = file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'fixtures'.\DIRECTORY_SEPARATOR.'bbb_logo.png');
+        $this->assertIsString($content);
+
+        $params->addPresentation('logo.png', $content);
 
         $result = $this->bbb->createMeeting($params);
 
diff --git a/tests/functional/BigBlueButtonWithCurlTransportTest.php b/tests/functional/BigBlueButtonWithCurlTransportTest.php
index 61d40766..c331a7c4 100644
--- a/tests/functional/BigBlueButtonWithCurlTransportTest.php
+++ b/tests/functional/BigBlueButtonWithCurlTransportTest.php
@@ -24,7 +24,7 @@
 use BigBlueButton\Http\Transport\CurlTransport;
 use BigBlueButton\Http\Transport\TransportInterface;
 
-final class BigBlueButtonWithCurlTransportTest extends AbstractBigBlueButtonFunctionalTest
+final class BigBlueButtonWithCurlTransportTest extends BigBlueButtonFunctionalTestAbstract
 {
     protected static function createTransport(): TransportInterface
     {
diff --git a/tests/functional/BigBlueButtonWithPsrHttpClientTransport.php b/tests/functional/BigBlueButtonWithPsrHttpClientTransport.php
index cd5bd19c..64d21dca 100644
--- a/tests/functional/BigBlueButtonWithPsrHttpClientTransport.php
+++ b/tests/functional/BigBlueButtonWithPsrHttpClientTransport.php
@@ -27,7 +27,7 @@
 use Symfony\Component\HttpClient\CurlHttpClient;
 use Symfony\Component\HttpClient\Psr18Client;
 
-final class BigBlueButtonWithPsrHttpClientTransport extends AbstractBigBlueButtonFunctionalTest
+final class BigBlueButtonWithPsrHttpClientTransport extends BigBlueButtonFunctionalTestAbstract
 {
     protected static function createTransport(): TransportInterface
     {
diff --git a/tests/functional/BigBlueButtonWithSymfonyHttpClientTransportTest.php b/tests/functional/BigBlueButtonWithSymfonyHttpClientTransportTest.php
index 3f75ce6f..d51e71f9 100644
--- a/tests/functional/BigBlueButtonWithSymfonyHttpClientTransportTest.php
+++ b/tests/functional/BigBlueButtonWithSymfonyHttpClientTransportTest.php
@@ -24,7 +24,7 @@
 use BigBlueButton\Http\Transport\Bridge\SymfonyHttpClient\SymfonyHttpClientTransport;
 use BigBlueButton\Http\Transport\TransportInterface;
 
-final class BigBlueButtonWithSymfonyHttpClientTransportTest extends AbstractBigBlueButtonFunctionalTest
+final class BigBlueButtonWithSymfonyHttpClientTransportTest extends BigBlueButtonFunctionalTestAbstract
 {
     protected static function createTransport(): TransportInterface
     {
diff --git a/tests/unit/BigBlueButtonTest.php b/tests/unit/BigBlueButtonTest.php
index 4410d474..eab2272a 100644
--- a/tests/unit/BigBlueButtonTest.php
+++ b/tests/unit/BigBlueButtonTest.php
@@ -292,6 +292,8 @@ public function testCreateWithPresentation(): void
                 $payload = $request->getPayload();
                 $xml = simplexml_load_string($payload);
 
+                self::assertNotFalse($xml);
+
                 $presentations = $xml->module[0];
                 $clientSettingsOverride = $xml->module[1];
 
diff --git a/tests/unit/Parameters/CreateMeetingParametersTest.php b/tests/unit/Parameters/CreateMeetingParametersTest.php
index 46d2e57c..f64933de 100644
--- a/tests/unit/Parameters/CreateMeetingParametersTest.php
+++ b/tests/unit/Parameters/CreateMeetingParametersTest.php
@@ -217,7 +217,11 @@ public function testGetPresentationsAsXMLWithFile(): void
     {
         $params = $this->generateCreateParams();
         $createMeetingParams = $this->getCreateMock($params);
-        $createMeetingParams->addPresentation('bbb_logo.png', file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'fixtures'.\DIRECTORY_SEPARATOR.'bbb_logo.png'));
+
+        $content = file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'fixtures'.\DIRECTORY_SEPARATOR.'bbb_logo.png');
+        $this->assertIsString($content);
+
+        $createMeetingParams->addPresentation('bbb_logo.png', $content);
         $this->assertXmlStringEqualsXmlFile(__DIR__.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'..'.\DIRECTORY_SEPARATOR.'fixtures'.\DIRECTORY_SEPARATOR.'presentation_with_embedded_file.xml', $createMeetingParams->getModules());
     }
 
diff --git a/tests/unit/Responses/GetMeetingsResponseTest.php b/tests/unit/Responses/GetMeetingsResponseTest.php
index fc3d2c31..e2a46054 100644
--- a/tests/unit/Responses/GetMeetingsResponseTest.php
+++ b/tests/unit/Responses/GetMeetingsResponseTest.php
@@ -85,12 +85,16 @@ public function testGetMeetingsNoMeetings(): void
     {
         // scalelite response no meetings
         $xml = simplexml_load_string('<response><returncode>SUCCESS</returncode><messageKey>noMeetings</messageKey><message>No meetings were found on this server.</message></response>');
+        $this->assertInstanceOf(\SimpleXMLElement::class, $xml);
+
         $this->meetings = new GetMeetingsResponse($xml);
         $this->assertEquals('SUCCESS', $this->meetings->getReturnCode());
         $this->assertCount(0, $this->meetings->getMeetings());
 
         // normal bbb response no meetings
         $xml = simplexml_load_string('<response><returncode>SUCCESS</returncode><meetings/><messageKey>noMeetings</messageKey><message>No meetings were found on this server.</message></response>');
+        $this->assertInstanceOf(\SimpleXMLElement::class, $xml);
+
         $this->meetings = new GetMeetingsResponse($xml);
         $this->assertEquals('SUCCESS', $this->meetings->getReturnCode());
         $this->assertCount(0, $this->meetings->getMeetings());
diff --git a/tests/unit/Responses/GetRecordingsResponseTest.php b/tests/unit/Responses/GetRecordingsResponseTest.php
index d95d8e6b..38bc372a 100644
--- a/tests/unit/Responses/GetRecordingsResponseTest.php
+++ b/tests/unit/Responses/GetRecordingsResponseTest.php
@@ -128,7 +128,10 @@ public function testHasNoRecordings(): void
           <message>There are no recordings for the meeting(s).</message>
         </response>';
 
-        $response = new GetRecordingsResponse(simplexml_load_string($xml));
+        $xml = simplexml_load_string($xml);
+        $this->assertInstanceOf(\SimpleXMLElement::class, $xml);
+
+        $response = new GetRecordingsResponse($xml);
 
         $this->assertTrue($response->hasNoRecordings());
     }
diff --git a/tests/unit/Responses/HooksDestroyResponseTest.php b/tests/unit/Responses/HooksDestroyResponseTest.php
index 7704ee1a..4838e7cf 100644
--- a/tests/unit/Responses/HooksDestroyResponseTest.php
+++ b/tests/unit/Responses/HooksDestroyResponseTest.php
@@ -53,6 +53,7 @@ public function testHooksDestroyResponseTypes(): void
     public function testHookDestroyMissingHook(): void
     {
         $xml = simplexml_load_string('<response><returncode>FAILED</returncode><messageKey>destroyMissingHook</messageKey><message>The hook informed was not found.</message></response>');
+        $this->assertInstanceOf(\SimpleXMLElement::class, $xml);
 
         $destroyResponse = new HooksDestroyResponse($xml);
         $this->assertTrue($destroyResponse->failed());
@@ -62,6 +63,7 @@ public function testHookDestroyMissingHook(): void
     public function testHookDestroyHookError(): void
     {
         $xml = simplexml_load_string('<response><returncode>FAILED</returncode><messageKey>destroyHookError</messageKey><message>An error happened while removing your hook. Check the logs.</message></response>');
+        $this->assertInstanceOf(\SimpleXMLElement::class, $xml);
 
         $destroyResponse = new HooksDestroyResponse($xml);
         $this->assertTrue($destroyResponse->failed());
diff --git a/tests/unit/Responses/InsertDocumentResponseTest.php b/tests/unit/Responses/InsertDocumentResponseTest.php
index 01d1012e..62899ad6 100644
--- a/tests/unit/Responses/InsertDocumentResponseTest.php
+++ b/tests/unit/Responses/InsertDocumentResponseTest.php
@@ -41,7 +41,12 @@ public function testIsMeetingRunningResponseContent(): void
     {
         $this->assertEquals('SUCCESS', $this->running->getReturnCode());
 
-        $this->assertEquals('<?xmlversion="1.0"?><response><returncode>SUCCESS</returncode></response>', $this->minifyString($this->running->getRawXml()->asXML()));
+        $xml = $this->running->getRawXml()->asXML();
+        $this->assertIsString($xml);
+
+        $this->assertEquals('<?xmlversion="1.0"?><response><returncode>SUCCESS</returncode></response>', $this->minifyString(
+            $xml
+        ));
     }
 
     public function testIsMeetingRunningResponseTypes(): void
diff --git a/tests/unit/Responses/IsMeetingRunningResponseTest.php b/tests/unit/Responses/IsMeetingRunningResponseTest.php
index 70dce13f..003cf7f2 100644
--- a/tests/unit/Responses/IsMeetingRunningResponseTest.php
+++ b/tests/unit/Responses/IsMeetingRunningResponseTest.php
@@ -43,7 +43,12 @@ public function testIsMeetingRunningResponseContent(): void
         $this->assertEquals('SUCCESS', $this->running->getReturnCode());
         $this->assertTrue($this->running->isRunning());
 
-        $this->assertEquals('<?xmlversion="1.0"?><response><returncode>SUCCESS</returncode><running>true</running></response>', $this->minifyString($this->running->getRawXml()->asXML()));
+        $xml = $this->running->getRawXml()->asXML();
+        $this->assertIsString($xml);
+
+        $this->assertEquals('<?xmlversion="1.0"?><response><returncode>SUCCESS</returncode><running>true</running></response>', $this->minifyString(
+            $xml
+        ));
     }
 
     public function testIsMeetingRunningResponseTypes(): void
diff --git a/tests/unit/Util/ArrayHelperTest.php b/tests/unit/Util/ArrayHelperTest.php
index 192e5ea6..917f2767 100644
--- a/tests/unit/Util/ArrayHelperTest.php
+++ b/tests/unit/Util/ArrayHelperTest.php
@@ -29,9 +29,7 @@
  */
 final class ArrayHelperTest extends TestCase
 {
-    /**
-     * @return iterable<array{0: array<mixed>, 1: array<mixed>, 2: bool, 3: array<mixed>}>
-     */
+    /** @return iterable<array<mixed>> */
     public static function provideArrays(): iterable
     {
         yield 'simple flat arrays' => [
@@ -63,9 +61,9 @@ public static function provideArrays(): iterable
     /**
      * @dataProvider provideArrays
      *
-     * @param array<mixed> $input1
-     * @param array<mixed> $input2
-     * @param array<mixed> $output
+     * @param array<string|array-key,string> $input1
+     * @param array<string|array-key,string> $input2
+     * @param array<string|array-key,string> $output
      */
     public function testMergeRecursive(array $input1, array $input2, bool $reorderNested, array $output): void
     {
diff --git a/tests/unit/Util/SimpleXMLElementExtendedTest.php b/tests/unit/Util/SimpleXMLElementExtendedTest.php
index c29a09c7..57dc6395 100644
--- a/tests/unit/Util/SimpleXMLElementExtendedTest.php
+++ b/tests/unit/Util/SimpleXMLElementExtendedTest.php
@@ -38,9 +38,13 @@ public function testAddChildWithCData(): void
         $module = $xml->addChildWithCData('module', '{"foo": {"foo": "baa"}}');
         $module->addAttribute('name', 'clientSettingsOverride');
 
+        $result = $xml->asXML();
+
+        $this->assertNotFalse($result);
+
         $expected = '<?xml version="1.0" encoding="UTF-8"?>
 <modules><module name="clientSettingsOverride"><![CDATA[{"foo": {"foo": "baa"}}]]></module></modules>';
 
-        $this->assertXmlStringEqualsXmlString($expected, $xml->asXML());
+        $this->assertXmlStringEqualsXmlString($expected, $result);
     }
 }