fix(Logger): keep running remaining handlers after one returns false

Logger::log() stopped executing any subsequent handlers as soon as one
handler's handle() returned false. In practice every shipped handler
(FileHandler, ErrorlogHandler) returns false purely to signal a write
failure, not a deliberate "stop the chain" request. This meant a single
FileHandler failure (e.g. bad file permissions) silently swallowed the
log message for every handler configured after it, such as an
ErrorlogHandler fallback.

None of the shipped handlers rely on the early-exit behavior, so drop
it: every configured, level-matching handler now runs regardless of
what earlier handlers returned.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GQ1FHzXX7To34G4mwQGN8U

Author: Alexandros-Pallis

system/Log/Handlers/HandlerInterface.php

@@ -19,10 +19,9 @@
 interface HandlerInterface
 {
     /**
-     * Handles logging the message.
-     * If the handler returns false, then execution of handlers
-     * will stop. Any handlers that have not run, yet, will not
-     * be run.
+     * Handles logging the message. All configured handlers that
+     * can handle the given level are run, regardless of whether
+     * this (or any other) handler returns false.
      *
      * @param string $level
      * @param string $message

system/Log/Logger.php

@@ -266,10 +266,7 @@ public function log($level, string|Stringable $message, array $context = []): vo
                 continue;
             }
 
-            // If the handler returns false, then we don't execute any other handlers.
-            if (! $handler->setDateFormat($this->dateFormat)->handle($level, $message)) {
-                break;
-            }
+            $handler->setDateFormat($this->dateFormat)->handle($level, $message);
         }
     }
 

tests/_support/Log/Handlers/FailingTestHandler.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Tests\Support\Log\Handlers;
+
+use CodeIgniter\Log\Handlers\BaseHandler;
+
+/**
+ * A LogHandler that always fails to handle the log message.
+ * Only used for testing purposes.
+ */
+class FailingTestHandler extends BaseHandler
+{
+    /**
+     * Number of times handle() has been called.
+     */
+    protected static int $timesCalled = 0;
+
+    public function __construct(array $config)
+    {
+        parent::__construct($config);
+
+        self::$timesCalled = 0;
+    }
+
+    public function handle($level, $message): bool
+    {
+        self::$timesCalled++;
+
+        return false;
+    }
+
+    public static function getTimesCalled(): int
+    {
+        return self::$timesCalled;
+    }
+}

tests/_support/Log/Handlers/TestHandler.php

@@ -50,9 +50,6 @@ public function __construct(array $config)
 
     /**
      * Handles logging the message.
-     * If the handler returns false, then execution of handlers
-     * will stop. Any handlers that have not run, yet, will not
-     * be run.
      *
      * @param string $level
      * @param string $message

tests/system/Log/LoggerTest.php

@@ -25,6 +25,7 @@
 use ReflectionNamedType;
 use stdClass;
 use Stringable;
+use Tests\Support\Log\Handlers\FailingTestHandler;
 use Tests\Support\Log\Handlers\TestHandler;
 
 /**
@@ -108,6 +109,28 @@ public function testLogDoesnotLogUnhandledLevels(): void
         $this->assertCount(0, $logs);
     }
 
+    public function testLogRunsRemainingHandlersWhenAnEarlierHandlerReturnsFalse(): void
+    {
+        $config = new LoggerConfig();
+
+        $config->handlers = [
+            FailingTestHandler::class => [
+                'handles' => ['debug'],
+            ],
+            TestHandler::class => [
+                'handles' => ['debug'],
+                'path'    => '',
+            ],
+        ];
+
+        $logger = new Logger($config);
+
+        $logger->log('debug', 'Test message');
+
+        $this->assertSame(1, FailingTestHandler::getTimesCalled());
+        $this->assertCount(1, TestHandler::getLogs());
+    }
+
     public function testLogInterpolatesMessage(): void
     {
         $config = new LoggerConfig();

user_guide_src/source/changelogs/v4.7.5.rst

@@ -52,6 +52,7 @@ Bugs Fixed
 - **Honeypot:** Fixed a bug where bot detection returned an HTTP 500 response instead of 403 (Forbidden).
 - **I18n:** Fixed a bug where ``Time::today()``, ``Time::yesterday()``, and ``Time::tomorrow()`` ignored the specified ``$timezone`` and ``setTestNow()`` when calculating the day.
 - **Logger:** Fixed a bug where interpolating a log message with array or non-stringable context values could raise PHP warnings or errors.
+- **Logger:** Fixed a bug where ``Logger::log()`` stopped running any remaining configured handlers after one handler returned ``false`` (e.g., ``FileHandler`` failing to open its log file due to file permissions), silently dropping the log message for every handler after it.
 - **Cache:** Fixed ``MemcachedHandler::decrement()`` initializing a non-existent counter to the positive offset. Missing counters are now initialized to ``0``, reflecting Memcached's unsigned, saturating counter semantics.
 
 See the repo's