diff --git a/packages/guides-cli/composer.json b/packages/guides-cli/composer.json
index 29c94a6da..09df05b5f 100644
--- a/packages/guides-cli/composer.json
+++ b/packages/guides-cli/composer.json
@@ -26,7 +26,7 @@
     ],
     "require": {
         "php": "^8.1",
-        "monolog/monolog": "^2.9 || ^3.0",
+        "monolog/monolog": "^3.0",
         "phpdocumentor/guides": "^1.0 || ^2.0",
         "phpdocumentor/guides-restructured-text": "^1.0 || ^2.0",
         "symfony/config": "^5.4 || ^6.3 || ^7.0",
diff --git a/packages/guides-cli/src/Command/Run.php b/packages/guides-cli/src/Command/Run.php
index aeebc66ca..da7cff393 100644
--- a/packages/guides-cli/src/Command/Run.php
+++ b/packages/guides-cli/src/Command/Run.php
@@ -256,7 +256,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
         }
 
         if ($settings->isFailOnError()) {
-            $spyProcessor = new SpyProcessor($settings->getFailOnError());
+            $spyProcessor = new SpyProcessor($settings->getFailOnError() ?? LogLevel::WARNING);
             $this->logger->pushProcessor($spyProcessor);
         }
 
diff --git a/packages/guides-cli/src/Logger/SpyProcessor.php b/packages/guides-cli/src/Logger/SpyProcessor.php
index 7a89faeff..05965fa39 100644
--- a/packages/guides-cli/src/Logger/SpyProcessor.php
+++ b/packages/guides-cli/src/Logger/SpyProcessor.php
@@ -13,6 +13,7 @@
 
 namespace phpDocumentor\Guides\Cli\Logger;
 
+use Monolog\Level;
 use Monolog\LogRecord;
 use Monolog\Processor\ProcessorInterface;
 use Psr\Log\LogLevel;
@@ -27,9 +28,16 @@
 final class SpyProcessor implements ProcessorInterface
 {
     private bool $hasBeenCalled = false;
+    private Level $level;
 
-    public function __construct(private string|null $level = LogLevel::WARNING)
+    /** @param LogLevel::* $level */
+    public function __construct(string|null $level = LogLevel::WARNING)
     {
+        if ($level === null) {
+            $level = LogLevel::WARNING;
+        }
+
+        $this->level = Level::fromName(strtolower($level));
     }
 
     public function hasBeenCalled(): bool
@@ -37,9 +45,9 @@ public function hasBeenCalled(): bool
         return $this->hasBeenCalled;
     }
 
-    public function __invoke(array|LogRecord $record): array|LogRecord
+    public function __invoke(LogRecord $record): LogRecord
     {
-        if (strtolower($record['level_name']) === $this->level) {
+        if ($this->level->includes($record->level)) {
             $this->hasBeenCalled = true;
         }
 
diff --git a/packages/guides-cli/tests/unit/Logger/SpyProcessorTest.php b/packages/guides-cli/tests/unit/Logger/SpyProcessorTest.php
index 4ead9c969..112240798 100644
--- a/packages/guides-cli/tests/unit/Logger/SpyProcessorTest.php
+++ b/packages/guides-cli/tests/unit/Logger/SpyProcessorTest.php
@@ -13,7 +13,11 @@
 
 namespace phpDocumentor\Guides\Cli\Logger;
 
+use DateTimeImmutable;
+use Monolog\Level;
+use Monolog\LogRecord;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\LogLevel;
 
 final class SpyProcessorTest extends TestCase
 {
@@ -27,7 +31,21 @@ public function testHasBeenCalledReturnsFalseByDefault(): void
     public function testItKnowsWhenALogIsEmitted(): void
     {
         $process = new SpyProcessor();
-        $process(['channel' => 'test', 'level_name' => 'warning']);
+        $process(new LogRecord(new DateTimeImmutable(), 'test', Level::Warning, 'test message'));
         self::assertTrue($process->hasBeenCalled());
     }
+
+    public function testItKnowsWhenAErrorIsEmitted(): void
+    {
+        $process = new SpyProcessor();
+        $process(new LogRecord(new DateTimeImmutable(), 'test', Level::Error, 'test message'));
+        self::assertTrue($process->hasBeenCalled());
+    }
+
+    public function testIsNotCalledWhenLevelIsTolow(): void
+    {
+        $process = new SpyProcessor(LogLevel::ERROR);
+        $process(new LogRecord(new DateTimeImmutable(), 'test', Level::Warning, 'test message'));
+        self::assertFalse($process->hasBeenCalled());
+    }
 }
diff --git a/packages/guides/src/Settings/ProjectSettings.php b/packages/guides/src/Settings/ProjectSettings.php
index 2c2bc28a0..35ec5ee66 100644
--- a/packages/guides/src/Settings/ProjectSettings.php
+++ b/packages/guides/src/Settings/ProjectSettings.php
@@ -14,6 +14,7 @@
 namespace phpDocumentor\Guides\Settings;
 
 use phpDocumentor\FileSystem\Finder\Exclude;
+use Psr\Log\LogLevel;
 
 final class ProjectSettings
 {
@@ -32,6 +33,8 @@ final class ProjectSettings
     /** @var string[]  */
     private array $outputFormats = ['html'];
     private string $logPath = 'php://stder';
+
+    /** @var LogLevel::*|null */
     private string|null $failOnError = null;
     private bool $showProgressBar = true;
     private bool $linksRelative = false;
@@ -135,11 +138,13 @@ public function isFailOnError(): bool
         return $this->failOnError !== null;
     }
 
+    /** @return LogLevel::* */
     public function getFailOnError(): string|null
     {
         return $this->failOnError;
     }
 
+    /** @param LogLevel::* $logLevel */
     public function setFailOnError(string $logLevel): void
     {
         $this->failOnError = $logLevel;
diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index d897bc64f..af4ba3b32 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -20,11 +20,6 @@ parameters:
 			count: 6
 			path: packages/guides-cli/src/Command/Run.php
 
-		-
-			message: "#^Parameter \\#1 \\$callback of method Monolog\\\\Logger\\:\\:pushProcessor\\(\\) expects callable\\(Monolog\\\\LogRecord\\)\\: Monolog\\\\LogRecord, phpDocumentor\\\\Guides\\\\Cli\\\\Logger\\\\SpyProcessor given\\.$#"
-			count: 1
-			path: packages/guides-cli/src/Command/Run.php
-
 		-
 			message: "#^Parameter \\#1 \\$documents of class phpDocumentor\\\\Guides\\\\Handlers\\\\CompileDocumentsCommand constructor expects array\\<phpDocumentor\\\\Guides\\\\Nodes\\\\DocumentNode\\>, mixed given\\.$#"
 			count: 1
@@ -65,21 +60,6 @@ parameters:
 			count: 1
 			path: packages/guides-cli/src/DependencyInjection/ContainerFactory.php
 
-		-
-			message: "#^Method phpDocumentor\\\\Guides\\\\Cli\\\\Logger\\\\SpyProcessor\\:\\:__invoke\\(\\) has parameter \\$record with no value type specified in iterable type array\\.$#"
-			count: 1
-			path: packages/guides-cli/src/Logger/SpyProcessor.php
-
-		-
-			message: "#^Method phpDocumentor\\\\Guides\\\\Cli\\\\Logger\\\\SpyProcessor\\:\\:__invoke\\(\\) return type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: packages/guides-cli/src/Logger/SpyProcessor.php
-
-		-
-			message: "#^Return type \\(array\\|Monolog\\\\LogRecord\\) of method phpDocumentor\\\\Guides\\\\Cli\\\\Logger\\\\SpyProcessor\\:\\:__invoke\\(\\) should be covariant with return type \\(Monolog\\\\LogRecord\\) of method Monolog\\\\Processor\\\\ProcessorInterface\\:\\:__invoke\\(\\)$#"
-			count: 1
-			path: packages/guides-cli/src/Logger/SpyProcessor.php
-
 		-
 			message: "#^Cannot call method end\\(\\) on Symfony\\\\Component\\\\Config\\\\Definition\\\\Builder\\\\NodeParentInterface\\|null\\.$#"
 			count: 1