diff --git a/admin/framework/composer.json b/admin/framework/composer.json
index 70b51ba8f88c..132932acc25d 100644
--- a/admin/framework/composer.json
+++ b/admin/framework/composer.json
@@ -15,7 +15,7 @@
         "ext-json": "*",
         "ext-mbstring": "*",
         "laminas/laminas-escaper": "^2.9",
-        "psr/log": "^1.1"
+        "psr/log": "^2.0"
     },
     "require-dev": {
         "codeigniter/coding-standard": "^1.5",
diff --git a/composer.json b/composer.json
index 3d9354754805..aeac6801da1b 100644
--- a/composer.json
+++ b/composer.json
@@ -15,7 +15,7 @@
         "ext-json": "*",
         "ext-mbstring": "*",
         "laminas/laminas-escaper": "^2.9",
-        "psr/log": "^1.1"
+        "psr/log": "^2.0"
     },
     "require-dev": {
         "codeigniter/coding-standard": "^1.5",
diff --git a/system/Common.php b/system/Common.php
index ebfd8e2565e8..4ec6cbbbadbf 100644
--- a/system/Common.php
+++ b/system/Common.php
@@ -794,7 +794,7 @@ function lang(string $line, array $args = [], ?string $locale = null)
      *  - info
      *  - debug
      *
-     * @return bool
+     * @return void
      */
     function log_message(string $level, string $message, array $context = [])
     {
@@ -804,10 +804,12 @@ function log_message(string $level, string $message, array $context = [])
         if (ENVIRONMENT === 'testing') {
             $logger = new TestLogger(new Logger());
 
-            return $logger->log($level, $message, $context);
+            $logger->log($level, $message, $context);
+
+            return;
         }
 
-        return Services::logger(true)->log($level, $message, $context); // @codeCoverageIgnore
+        Services::logger(true)->log($level, $message, $context); // @codeCoverageIgnore
     }
 }
 
diff --git a/system/ComposerScripts.php b/system/ComposerScripts.php
index b95bdf54c4ae..021079da468d 100644
--- a/system/ComposerScripts.php
+++ b/system/ComposerScripts.php
@@ -56,7 +56,7 @@ final class ComposerScripts
         ],
         'psr-log' => [
             'license' => __DIR__ . '/../vendor/psr/log/LICENSE',
-            'from'    => __DIR__ . '/../vendor/psr/log/Psr/Log/',
+            'from'    => __DIR__ . '/../vendor/psr/log/src/',
             'to'      => __DIR__ . '/ThirdParty/PSR/Log/',
         ],
     ];
@@ -84,7 +84,6 @@ public static function postUpdate()
         }
 
         self::copyKintInitFiles();
-        self::recursiveDelete(self::$dependencies['psr-log']['to'] . 'Test/');
     }
 
     /**
diff --git a/system/Log/Logger.php b/system/Log/Logger.php
index b1583f5d789c..4d4e36a8afad 100644
--- a/system/Log/Logger.php
+++ b/system/Log/Logger.php
@@ -15,6 +15,7 @@
 use CodeIgniter\Log\Handlers\HandlerInterface;
 use Psr\Log\LoggerInterface;
 use RuntimeException;
+use Stringable;
 use Throwable;
 
 /**
@@ -157,9 +158,9 @@ public function __construct($config, bool $debug = CI_DEBUG)
      *
      * @param string $message
      */
-    public function emergency($message, array $context = []): bool
+    public function emergency(string|Stringable $message, array $context = []): void
     {
-        return $this->log('emergency', $message, $context);
+        $this->log('emergency', $message, $context);
     }
 
     /**
@@ -170,9 +171,9 @@ public function emergency($message, array $context = []): bool
      *
      * @param string $message
      */
-    public function alert($message, array $context = []): bool
+    public function alert(string|Stringable $message, array $context = []): void
     {
-        return $this->log('alert', $message, $context);
+        $this->log('alert', $message, $context);
     }
 
     /**
@@ -182,9 +183,9 @@ public function alert($message, array $context = []): bool
      *
      * @param string $message
      */
-    public function critical($message, array $context = []): bool
+    public function critical(string|Stringable $message, array $context = []): void
     {
-        return $this->log('critical', $message, $context);
+        $this->log('critical', $message, $context);
     }
 
     /**
@@ -193,9 +194,9 @@ public function critical($message, array $context = []): bool
      *
      * @param string $message
      */
-    public function error($message, array $context = []): bool
+    public function error(string|Stringable $message, array $context = []): void
     {
-        return $this->log('error', $message, $context);
+        $this->log('error', $message, $context);
     }
 
     /**
@@ -206,9 +207,9 @@ public function error($message, array $context = []): bool
      *
      * @param string $message
      */
-    public function warning($message, array $context = []): bool
+    public function warning(string|Stringable $message, array $context = []): void
     {
-        return $this->log('warning', $message, $context);
+        $this->log('warning', $message, $context);
     }
 
     /**
@@ -216,9 +217,9 @@ public function warning($message, array $context = []): bool
      *
      * @param string $message
      */
-    public function notice($message, array $context = []): bool
+    public function notice(string|Stringable $message, array $context = []): void
     {
-        return $this->log('notice', $message, $context);
+        $this->log('notice', $message, $context);
     }
 
     /**
@@ -228,9 +229,9 @@ public function notice($message, array $context = []): bool
      *
      * @param string $message
      */
-    public function info($message, array $context = []): bool
+    public function info(string|Stringable $message, array $context = []): void
     {
-        return $this->log('info', $message, $context);
+        $this->log('info', $message, $context);
     }
 
     /**
@@ -238,9 +239,9 @@ public function info($message, array $context = []): bool
      *
      * @param string $message
      */
-    public function debug($message, array $context = []): bool
+    public function debug(string|Stringable $message, array $context = []): void
     {
-        return $this->log('debug', $message, $context);
+        $this->log('debug', $message, $context);
     }
 
     /**
@@ -249,7 +250,7 @@ public function debug($message, array $context = []): bool
      * @param string $level
      * @param string $message
      */
-    public function log($level, $message, array $context = []): bool
+    public function log($level, string|Stringable $message, array $context = []): void
     {
         if (is_numeric($level)) {
             $level = array_search((int) $level, $this->logLevels, true);
@@ -262,7 +263,7 @@ public function log($level, $message, array $context = []): bool
 
         // Does the app want to log this right now?
         if (! in_array($level, $this->loggableLevels, true)) {
-            return false;
+            return;
         }
 
         // Parse our placeholders
@@ -295,8 +296,6 @@ public function log($level, $message, array $context = []): bool
                 break;
             }
         }
-
-        return true;
     }
 
     /**
diff --git a/system/Test/TestLogger.php b/system/Test/TestLogger.php
index 240f5c6d95b5..dce1277d98d2 100644
--- a/system/Test/TestLogger.php
+++ b/system/Test/TestLogger.php
@@ -12,6 +12,7 @@
 namespace CodeIgniter\Test;
 
 use CodeIgniter\Log\Logger;
+use Stringable;
 
 /**
  * @see \CodeIgniter\Test\TestLoggerTest
@@ -27,7 +28,7 @@ class TestLogger extends Logger
      * @param string $level
      * @param string $message
      */
-    public function log($level, $message, array $context = []): bool
+    public function log($level, string|Stringable $message, array $context = []): void
     {
         // While this requires duplicate work, we want to ensure
         // we have the final message to test against.
@@ -52,7 +53,7 @@ public function log($level, $message, array $context = []): bool
         ];
 
         // Let the parent do it's thing.
-        return parent::log($level, $message, $context);
+        parent::log($level, $message, $context);
     }
 
     /**
diff --git a/system/ThirdParty/PSR/Log/AbstractLogger.php b/system/ThirdParty/PSR/Log/AbstractLogger.php
index e02f9daf3d51..d60a091affae 100644
--- a/system/ThirdParty/PSR/Log/AbstractLogger.php
+++ b/system/ThirdParty/PSR/Log/AbstractLogger.php
@@ -11,118 +11,5 @@
  */
 abstract class AbstractLogger implements LoggerInterface
 {
-    /**
-     * System is unusable.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function emergency($message, array $context = array())
-    {
-        $this->log(LogLevel::EMERGENCY, $message, $context);
-    }
-
-    /**
-     * Action must be taken immediately.
-     *
-     * Example: Entire website down, database unavailable, etc. This should
-     * trigger the SMS alerts and wake you up.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function alert($message, array $context = array())
-    {
-        $this->log(LogLevel::ALERT, $message, $context);
-    }
-
-    /**
-     * Critical conditions.
-     *
-     * Example: Application component unavailable, unexpected exception.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function critical($message, array $context = array())
-    {
-        $this->log(LogLevel::CRITICAL, $message, $context);
-    }
-
-    /**
-     * Runtime errors that do not require immediate action but should typically
-     * be logged and monitored.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function error($message, array $context = array())
-    {
-        $this->log(LogLevel::ERROR, $message, $context);
-    }
-
-    /**
-     * Exceptional occurrences that are not errors.
-     *
-     * Example: Use of deprecated APIs, poor use of an API, undesirable things
-     * that are not necessarily wrong.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function warning($message, array $context = array())
-    {
-        $this->log(LogLevel::WARNING, $message, $context);
-    }
-
-    /**
-     * Normal but significant events.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function notice($message, array $context = array())
-    {
-        $this->log(LogLevel::NOTICE, $message, $context);
-    }
-
-    /**
-     * Interesting events.
-     *
-     * Example: User logs in, SQL logs.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function info($message, array $context = array())
-    {
-        $this->log(LogLevel::INFO, $message, $context);
-    }
-
-    /**
-     * Detailed debug information.
-     *
-     * @param string  $message
-     * @param mixed[] $context
-     *
-     * @return void
-     */
-    public function debug($message, array $context = array())
-    {
-        $this->log(LogLevel::DEBUG, $message, $context);
-    }
+    use LoggerTrait;
 }
diff --git a/system/ThirdParty/PSR/Log/LoggerAwareTrait.php b/system/ThirdParty/PSR/Log/LoggerAwareTrait.php
index 82bf45c89bab..5f1553a4c810 100644
--- a/system/ThirdParty/PSR/Log/LoggerAwareTrait.php
+++ b/system/ThirdParty/PSR/Log/LoggerAwareTrait.php
@@ -12,7 +12,7 @@ trait LoggerAwareTrait
      *
      * @var LoggerInterface|null
      */
-    protected $logger;
+    protected ?LoggerInterface $logger = null;
 
     /**
      * Sets a logger.
diff --git a/system/ThirdParty/PSR/Log/LoggerInterface.php b/system/ThirdParty/PSR/Log/LoggerInterface.php
index 2206cfde41ae..b4d062b9b640 100644
--- a/system/ThirdParty/PSR/Log/LoggerInterface.php
+++ b/system/ThirdParty/PSR/Log/LoggerInterface.php
@@ -22,12 +22,12 @@ interface LoggerInterface
     /**
      * System is unusable.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function emergency($message, array $context = array());
+    public function emergency(string|\Stringable $message, array $context = []);
 
     /**
      * Action must be taken immediately.
@@ -35,35 +35,35 @@ public function emergency($message, array $context = array());
      * Example: Entire website down, database unavailable, etc. This should
      * trigger the SMS alerts and wake you up.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function alert($message, array $context = array());
+    public function alert(string|\Stringable $message, array $context = []);
 
     /**
      * Critical conditions.
      *
      * Example: Application component unavailable, unexpected exception.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function critical($message, array $context = array());
+    public function critical(string|\Stringable $message, array $context = []);
 
     /**
      * Runtime errors that do not require immediate action but should typically
      * be logged and monitored.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function error($message, array $context = array());
+    public function error(string|\Stringable $message, array $context = []);
 
     /**
      * Exceptional occurrences that are not errors.
@@ -71,55 +71,55 @@ public function error($message, array $context = array());
      * Example: Use of deprecated APIs, poor use of an API, undesirable things
      * that are not necessarily wrong.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function warning($message, array $context = array());
+    public function warning(string|\Stringable $message, array $context = []);
 
     /**
      * Normal but significant events.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function notice($message, array $context = array());
+    public function notice(string|\Stringable $message, array $context = []);
 
     /**
      * Interesting events.
      *
      * Example: User logs in, SQL logs.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function info($message, array $context = array());
+    public function info(string|\Stringable $message, array $context = []);
 
     /**
      * Detailed debug information.
      *
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      */
-    public function debug($message, array $context = array());
+    public function debug(string|\Stringable $message, array $context = []);
 
     /**
      * Logs with an arbitrary level.
      *
      * @param mixed   $level
-     * @param string  $message
+     * @param string|\Stringable $message
      * @param mixed[] $context
      *
      * @return void
      *
      * @throws \Psr\Log\InvalidArgumentException
      */
-    public function log($level, $message, array $context = array());
+    public function log($level, string|\Stringable $message, array $context = []);
 }
diff --git a/system/ThirdParty/PSR/Log/LoggerTrait.php b/system/ThirdParty/PSR/Log/LoggerTrait.php
index e392fef0a0cb..920bda77f835 100644
--- a/system/ThirdParty/PSR/Log/LoggerTrait.php
+++ b/system/ThirdParty/PSR/Log/LoggerTrait.php
@@ -15,12 +15,12 @@ trait LoggerTrait
     /**
      * System is unusable.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function emergency($message, array $context = array())
+    public function emergency(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::EMERGENCY, $message, $context);
     }
@@ -31,12 +31,12 @@ public function emergency($message, array $context = array())
      * Example: Entire website down, database unavailable, etc. This should
      * trigger the SMS alerts and wake you up.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function alert($message, array $context = array())
+    public function alert(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::ALERT, $message, $context);
     }
@@ -46,12 +46,12 @@ public function alert($message, array $context = array())
      *
      * Example: Application component unavailable, unexpected exception.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function critical($message, array $context = array())
+    public function critical(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::CRITICAL, $message, $context);
     }
@@ -60,12 +60,12 @@ public function critical($message, array $context = array())
      * Runtime errors that do not require immediate action but should typically
      * be logged and monitored.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function error($message, array $context = array())
+    public function error(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::ERROR, $message, $context);
     }
@@ -76,12 +76,12 @@ public function error($message, array $context = array())
      * Example: Use of deprecated APIs, poor use of an API, undesirable things
      * that are not necessarily wrong.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function warning($message, array $context = array())
+    public function warning(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::WARNING, $message, $context);
     }
@@ -89,12 +89,12 @@ public function warning($message, array $context = array())
     /**
      * Normal but significant events.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function notice($message, array $context = array())
+    public function notice(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::NOTICE, $message, $context);
     }
@@ -104,12 +104,12 @@ public function notice($message, array $context = array())
      *
      * Example: User logs in, SQL logs.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function info($message, array $context = array())
+    public function info(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::INFO, $message, $context);
     }
@@ -117,12 +117,12 @@ public function info($message, array $context = array())
     /**
      * Detailed debug information.
      *
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      */
-    public function debug($message, array $context = array())
+    public function debug(string|\Stringable $message, array $context = [])
     {
         $this->log(LogLevel::DEBUG, $message, $context);
     }
@@ -131,12 +131,12 @@ public function debug($message, array $context = array())
      * Logs with an arbitrary level.
      *
      * @param mixed  $level
-     * @param string $message
+     * @param string|\Stringable $message
      * @param array  $context
      *
      * @return void
      *
      * @throws \Psr\Log\InvalidArgumentException
      */
-    abstract public function log($level, $message, array $context = array());
+    abstract public function log($level, string|\Stringable $message, array $context = []);
 }
diff --git a/system/ThirdParty/PSR/Log/NullLogger.php b/system/ThirdParty/PSR/Log/NullLogger.php
index c8f7293b1c66..56077057159d 100644
--- a/system/ThirdParty/PSR/Log/NullLogger.php
+++ b/system/ThirdParty/PSR/Log/NullLogger.php
@@ -16,14 +16,14 @@ class NullLogger extends AbstractLogger
      * Logs with an arbitrary level.
      *
      * @param mixed  $level
-     * @param string $message
-     * @param array  $context
+     * @param string|\Stringable $message
+     * @param array $context
      *
      * @return void
      *
      * @throws \Psr\Log\InvalidArgumentException
      */
-    public function log($level, $message, array $context = array())
+    public function log($level, string|\Stringable $message, array $context = [])
     {
         // noop
     }
diff --git a/tests/system/Log/LoggerTest.php b/tests/system/Log/LoggerTest.php
index 317ad9c14bf4..8087ff645845 100644
--- a/tests/system/Log/LoggerTest.php
+++ b/tests/system/Log/LoggerTest.php
@@ -17,6 +17,7 @@
 use CodeIgniter\Test\Mock\MockLogger as LoggerConfig;
 use Exception;
 use Tests\Support\Log\Handlers\TestHandler;
+use TypeError;
 
 /**
  * @internal
@@ -48,14 +49,14 @@ public function testLogThrowsExceptionOnInvalidLevel(): void
         $logger->log('foo', '');
     }
 
-    public function testLogReturnsFalseWhenLogNotHandled(): void
+    public function testLogAlwaysReturnsVoid(): void
     {
         $config            = new LoggerConfig();
         $config->threshold = 3;
 
         $logger = new Logger($config);
 
-        $this->assertFalse($logger->log('debug', ''));
+        $this->assertNull($logger->log('debug', ''));
     }
 
     public function testLogActuallyLogs(): void
@@ -361,16 +362,12 @@ public function testLogLevels(): void
 
     public function testNonStringMessage(): void
     {
+        $this->expectException(TypeError::class);
+
         $config = new LoggerConfig();
         $logger = new Logger($config);
 
-        $expected = '[Tests\Support\Log\Handlers\TestHandler]';
         $logger->log(5, $config);
-
-        $logs = TestHandler::getLogs();
-
-        $this->assertCount(1, $logs);
-        $this->assertStringContainsString($expected, $logs[0]);
     }
 
     public function testDetermineFileNoStackTrace(): void
diff --git a/user_guide_src/source/changelogs/v4.5.0.rst b/user_guide_src/source/changelogs/v4.5.0.rst
index 50dae35cd5a2..8bff44c26ab0 100644
--- a/user_guide_src/source/changelogs/v4.5.0.rst
+++ b/user_guide_src/source/changelogs/v4.5.0.rst
@@ -21,12 +21,28 @@ BREAKING
 Behavior Changes
 ================
 
+- **Logger:** The :php:func:`log_message()` function and the logger methods in
+  ``CodeIgniter\Log\Logger`` now do not return ``bool`` values. The return types
+  have been fixed to ``void`` to follow the PSR-3 interface.
+
 Interface Changes
 =================
 
+.. note:: As long as you have not extended the relevant CodeIgniter core classes
+    or implemented these interfaces, all these changes are backward compatible
+    and require no intervention.
+
+- **Logger:** The `psr/log <https://packagist.org/packages/psr/log>`_ package has
+  been upgraded to v2.0.0.
+
 Method Signature Changes
 ========================
 
+- **Logger:** The method signatures of the methods in ``CodeIgniter\Log\Logger``
+  that implements the PSR-3 interface have been fixed. The ``bool`` return
+  types are changed to ``void``. The ``$message`` parameters now have
+  ``string|Stringable`` types.
+
 .. _v450-removed-deprecated-items:
 
 Removed Deprecated Items
diff --git a/user_guide_src/source/general/common_functions.rst b/user_guide_src/source/general/common_functions.rst
index a7b701241007..846273551ea5 100755
--- a/user_guide_src/source/general/common_functions.rst
+++ b/user_guide_src/source/general/common_functions.rst
@@ -324,13 +324,17 @@ Miscellaneous Functions
     :param   string   $level: The level of severity
     :param   string   $message: The message that is to be logged.
     :param   array    $context: An associative array of tags and their values that should be replaced in $message
-    :returns: true if was logged successfully or false if there was a problem logging it
+    :returns: void
     :rtype: bool
 
+    .. note:: Since v4.5.0, the return value is fixed to be compatible with PSR
+        Log. In previous versions, it returned ``true`` if was logged successfully
+        or ``false`` if there was a problem logging it.
+
     Logs a message using the Log Handlers defined in **app/Config/Logger.php**.
 
-    Level can be one of the following values: **emergency**, **alert**, **critical**, **error**, **warning**,
-    **notice**, **info**, or **debug**.
+    Level can be one of the following values: ``emergency``, ``alert``, ``critical``, ``error``, ``warning``,
+    ``notice``, ``info``, or ``debug``.
 
     Context can be used to substitute values in the message string. For full details, see the
     :doc:`Logging Information <logging>` page.