diff --git a/composer.json b/composer.json
index df4f57b2..6efd2819 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
     "require-dev": {
         "phpunit/phpunit": "^5.0",
         "graylog2/gelf-php": "~1.0",
-        "raven/raven": "^0.13",
+        "sentry/sentry": "^0.13",
         "ruflin/elastica": ">=0.90 <3.0",
         "doctrine/couchdb": "~1.0@dev",
         "aws/aws-sdk-php": "^2.4.9",
@@ -30,7 +30,7 @@
     },
     "suggest": {
         "graylog2/gelf-php": "Allow sending log messages to a GrayLog2 server",
-        "raven/raven": "Allow sending log messages to a Sentry server",
+        "sentry/sentry": "Allow sending log messages to a Sentry server",
         "doctrine/couchdb": "Allow sending log messages to a CouchDB server",
         "ruflin/elastica": "Allow sending log messages to an Elastic Search server",
         "php-amqplib/php-amqplib": "Allow sending log messages to an AMQP server using php-amqplib",
diff --git a/src/Monolog/Formatter/GelfMessageFormatter.php b/src/Monolog/Formatter/GelfMessageFormatter.php
index b4de509d..64e76652 100644
--- a/src/Monolog/Formatter/GelfMessageFormatter.php
+++ b/src/Monolog/Formatter/GelfMessageFormatter.php
@@ -106,7 +106,7 @@ class GelfMessageFormatter extends NormalizerFormatter
         }
 
         foreach ($record['extra'] as $key => $val) {
-            $val = is_scalar($val) ? $val : $this->toJson($val);
+            $val = is_scalar($val) || null === $val ? $val : $this->toJson($val);
             $len += strlen($this->extraPrefix . $key . $val);
             if ($len > self::MAX_LENGTH) {
                 $message->setAdditional($this->extraPrefix . $key, substr($val, 0, self::MAX_LENGTH - $len));
@@ -116,7 +116,7 @@ class GelfMessageFormatter extends NormalizerFormatter
         }
 
         foreach ($record['context'] as $key => $val) {
-            $val = is_scalar($val) ? $val : $this->toJson($val);
+            $val = is_scalar($val) || null === $val ? $val : $this->toJson($val);
             $len += strlen($this->contextPrefix . $key . $val);
             if ($len > self::MAX_LENGTH) {
                 $message->setAdditional($this->contextPrefix . $key, substr($val, 0, self::MAX_LENGTH - $len));
diff --git a/src/Monolog/Formatter/JsonFormatter.php b/src/Monolog/Formatter/JsonFormatter.php
index 06e9d13d..a985e2ab 100644
--- a/src/Monolog/Formatter/JsonFormatter.php
+++ b/src/Monolog/Formatter/JsonFormatter.php
@@ -186,6 +186,9 @@ class JsonFormatter extends NormalizerFormatter
             foreach ($trace as $frame) {
                 if (isset($frame['file'])) {
                     $data['trace'][] = $frame['file'].':'.$frame['line'];
+                } elseif (isset($frame['function']) && $frame['function'] === '{closure}') {
+                    // We should again normalize the frames, because it might contain invalid items
+                    $data['trace'][] = $frame['function'];
                 } else {
                     // We should again normalize the frames, because it might contain invalid items
                     $data['trace'][] = $this->normalize($frame);
diff --git a/src/Monolog/Formatter/NormalizerFormatter.php b/src/Monolog/Formatter/NormalizerFormatter.php
index 0f2844be..f4cdf460 100644
--- a/src/Monolog/Formatter/NormalizerFormatter.php
+++ b/src/Monolog/Formatter/NormalizerFormatter.php
@@ -129,6 +129,9 @@ class NormalizerFormatter implements FormatterInterface
         foreach ($trace as $frame) {
             if (isset($frame['file'])) {
                 $data['trace'][] = $frame['file'].':'.$frame['line'];
+            } elseif (isset($frame['function']) && $frame['function'] === '{closure}') {
+                // We should again normalize the frames, because it might contain invalid items
+                $data['trace'][] = $frame['function'];
             } else {
                 // We should again normalize the frames, because it might contain invalid items
                 $data['trace'][] = $this->toJson($this->normalize($frame), true);
diff --git a/src/Monolog/Handler/FingersCrossedHandler.php b/src/Monolog/Handler/FingersCrossedHandler.php
index d1c246be..dd7ddfb4 100644
--- a/src/Monolog/Handler/FingersCrossedHandler.php
+++ b/src/Monolog/Handler/FingersCrossedHandler.php
@@ -81,6 +81,26 @@ class FingersCrossedHandler extends Handler implements ProcessableHandlerInterfa
         return true;
     }
 
+    /**
+     * Manually activate this logger regardless of the activation strategy
+     */
+    public function activate()
+    {
+        if ($this->stopBuffering) {
+            $this->buffering = false;
+        }
+        if (!$this->handler instanceof HandlerInterface) {
+            $record = end($this->buffer) ?: null;
+
+            $this->handler = call_user_func($this->handler, $record, $this);
+            if (!$this->handler instanceof HandlerInterface) {
+                throw new \RuntimeException("The factory callable should return a HandlerInterface");
+            }
+        }
+        $this->handler->handleBatch($this->buffer);
+        $this->buffer = array();
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -96,17 +116,7 @@ class FingersCrossedHandler extends Handler implements ProcessableHandlerInterfa
                 array_shift($this->buffer);
             }
             if ($this->activationStrategy->isHandlerActivated($record)) {
-                if ($this->stopBuffering) {
-                    $this->buffering = false;
-                }
-                if (!$this->handler instanceof HandlerInterface) {
-                    $this->handler = call_user_func($this->handler, $record, $this);
-                    if (!$this->handler instanceof HandlerInterface) {
-                        throw new \RuntimeException("The factory callable should return a HandlerInterface");
-                    }
-                }
-                $this->handler->handleBatch($this->buffer);
-                $this->buffer = array();
+                $this->activate();
             }
         } else {
             $this->handler->handle($record);
diff --git a/src/Monolog/Handler/NewRelicHandler.php b/src/Monolog/Handler/NewRelicHandler.php
index e23078bf..2b27a16f 100644
--- a/src/Monolog/Handler/NewRelicHandler.php
+++ b/src/Monolog/Handler/NewRelicHandler.php
@@ -92,23 +92,27 @@ class NewRelicHandler extends AbstractProcessingHandler
             newrelic_notice_error($record['message']);
         }
 
-        foreach ($record['formatted']['context'] as $key => $parameter) {
-            if (is_array($parameter) && $this->explodeArrays) {
-                foreach ($parameter as $paramKey => $paramValue) {
-                    $this->setNewRelicParameter('context_' . $key . '_' . $paramKey, $paramValue);
+        if (isset($record['formatted']['context'])) {
+            foreach ($record['formatted']['context'] as $key => $parameter) {
+                if (is_array($parameter) && $this->explodeArrays) {
+                    foreach ($parameter as $paramKey => $paramValue) {
+                        $this->setNewRelicParameter('context_' . $key . '_' . $paramKey, $paramValue);
+                    }
+                } else {
+                    $this->setNewRelicParameter('context_' . $key, $parameter);
                 }
-            } else {
-                $this->setNewRelicParameter('context_' . $key, $parameter);
             }
         }
 
-        foreach ($record['formatted']['extra'] as $key => $parameter) {
-            if (is_array($parameter) && $this->explodeArrays) {
-                foreach ($parameter as $paramKey => $paramValue) {
-                    $this->setNewRelicParameter('extra_' . $key . '_' . $paramKey, $paramValue);
+        if (isset($record['formatted']['extra'])) {
+            foreach ($record['formatted']['extra'] as $key => $parameter) {
+                if (is_array($parameter) && $this->explodeArrays) {
+                    foreach ($parameter as $paramKey => $paramValue) {
+                        $this->setNewRelicParameter('extra_' . $key . '_' . $paramKey, $paramValue);
+                    }
+                } else {
+                    $this->setNewRelicParameter('extra_' . $key, $parameter);
                 }
-            } else {
-                $this->setNewRelicParameter('extra_' . $key, $parameter);
             }
         }
     }
diff --git a/src/Monolog/Handler/RotatingFileHandler.php b/src/Monolog/Handler/RotatingFileHandler.php
index 22e6c3dc..cd938057 100644
--- a/src/Monolog/Handler/RotatingFileHandler.php
+++ b/src/Monolog/Handler/RotatingFileHandler.php
@@ -24,6 +24,10 @@ use Monolog\Logger;
  */
 class RotatingFileHandler extends StreamHandler
 {
+    const FILE_PER_DAY = 'Y-m-d';
+    const FILE_PER_MONTH = 'Y-m';
+    const FILE_PER_YEAR = 'Y';
+
     protected $filename;
     protected $maxFiles;
     protected $mustRotate;
@@ -64,6 +68,20 @@ class RotatingFileHandler extends StreamHandler
 
     public function setFilenameFormat($filenameFormat, $dateFormat)
     {
+        if (!in_array($dateFormat, array(self::FILE_PER_DAY, self::FILE_PER_MONTH, self::FILE_PER_YEAR))) {
+            trigger_error(
+                'Invalid date format - format should be one of '.
+                'RotatingFileHandler::FILE_PER_DAY, RotatingFileHandler::FILE_PER_MONTH '.
+                'or RotatingFileHandler::FILE_PER_YEAR.',
+                E_USER_DEPRECATED
+            );
+        }
+        if (substr_count($filenameFormat, '{date}') === 0) {
+            trigger_error(
+                'Invalid filename format - format should contain at least `{date}`, because otherwise rotating is impossible.',
+                E_USER_DEPRECATED
+            );
+        }
         $this->filenameFormat = $filenameFormat;
         $this->dateFormat = $dateFormat;
         $this->url = $this->getTimedFilename();
diff --git a/src/Monolog/Handler/WhatFailureGroupHandler.php b/src/Monolog/Handler/WhatFailureGroupHandler.php
index e5533a6e..db793869 100644
--- a/src/Monolog/Handler/WhatFailureGroupHandler.php
+++ b/src/Monolog/Handler/WhatFailureGroupHandler.php
@@ -35,6 +35,8 @@ class WhatFailureGroupHandler extends GroupHandler
                 $handler->handle($record);
             } catch (\Exception $e) {
                 // What failure?
+            } catch (\Throwable $e) {
+                // What failure?
             }
         }
 
@@ -51,6 +53,8 @@ class WhatFailureGroupHandler extends GroupHandler
                 $handler->handleBatch($records);
             } catch (\Exception $e) {
                 // What failure?
+            } catch (\Throwable $e) {
+                // What failure?
             }
         }
     }
diff --git a/tests/Monolog/Handler/FingersCrossedHandlerTest.php b/tests/Monolog/Handler/FingersCrossedHandlerTest.php
index 8e31e9b8..b92bf437 100644
--- a/tests/Monolog/Handler/FingersCrossedHandlerTest.php
+++ b/tests/Monolog/Handler/FingersCrossedHandlerTest.php
@@ -22,6 +22,7 @@ class FingersCrossedHandlerTest extends TestCase
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::__construct
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      */
     public function testHandleBuffers()
     {
@@ -39,6 +40,7 @@ class FingersCrossedHandlerTest extends TestCase
 
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      */
     public function testHandleStopsBufferingAfterTrigger()
     {
@@ -53,6 +55,7 @@ class FingersCrossedHandlerTest extends TestCase
 
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      * @covers Monolog\Handler\FingersCrossedHandler::reset
      */
     public function testHandleRestartBufferingAfterReset()
@@ -71,6 +74,7 @@ class FingersCrossedHandlerTest extends TestCase
 
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      */
     public function testHandleRestartBufferingAfterBeingTriggeredWhenStopBufferingIsDisabled()
     {
@@ -87,6 +91,7 @@ class FingersCrossedHandlerTest extends TestCase
 
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      */
     public function testHandleBufferLimit()
     {
@@ -103,6 +108,7 @@ class FingersCrossedHandlerTest extends TestCase
 
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      */
     public function testHandleWithCallback()
     {
@@ -121,6 +127,7 @@ class FingersCrossedHandlerTest extends TestCase
 
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      * @expectedException RuntimeException
      */
     public function testHandleWithBadCallbackThrowsException()
@@ -173,6 +180,22 @@ class FingersCrossedHandlerTest extends TestCase
         $this->assertTrue($test->hasWarningRecords());
     }
 
+    /**
+     * @covers Monolog\Handler\FingersCrossedHandler::__construct
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
+     */
+    public function testOverrideActivationStrategy()
+    {
+        $test = new TestHandler();
+        $handler = new FingersCrossedHandler($test, new ErrorLevelActivationStrategy('warning'));
+        $handler->handle($this->getRecord(Logger::DEBUG));
+        $this->assertFalse($test->hasDebugRecords());
+        $handler->activate();
+        $this->assertTrue($test->hasDebugRecords());
+        $handler->handle($this->getRecord(Logger::INFO));
+        $this->assertTrue($test->hasInfoRecords());
+    }
+
     /**
      * @covers Monolog\Handler\FingersCrossed\ChannelLevelActivationStrategy::__construct
      * @covers Monolog\Handler\FingersCrossed\ChannelLevelActivationStrategy::isHandlerActivated
@@ -209,6 +232,7 @@ class FingersCrossedHandlerTest extends TestCase
 
     /**
      * @covers Monolog\Handler\FingersCrossedHandler::handle
+     * @covers Monolog\Handler\FingersCrossedHandler::activate
      */
     public function testHandleUsesProcessors()
     {
diff --git a/tests/Monolog/Handler/NewRelicHandlerTest.php b/tests/Monolog/Handler/NewRelicHandlerTest.php
index 4eda6155..4d3a615f 100644
--- a/tests/Monolog/Handler/NewRelicHandlerTest.php
+++ b/tests/Monolog/Handler/NewRelicHandlerTest.php
@@ -11,6 +11,7 @@
 
 namespace Monolog\Handler;
 
+use Monolog\Formatter\LineFormatter;
 use Monolog\TestCase;
 use Monolog\Logger;
 
@@ -104,6 +105,13 @@ class NewRelicHandlerTest extends TestCase
         $this->assertEquals($expected, self::$customParameters);
     }
 
+    public function testThehandlerCanHandleTheRecordsFormattedUsingTheLineFormatter()
+    {
+        $handler = new StubNewRelicHandler();
+        $handler->setFormatter(new LineFormatter());
+        $handler->handle($this->getRecord(Logger::ERROR));
+    }
+
     public function testTheAppNameIsNullByDefault()
     {
         $handler = new StubNewRelicHandler();
diff --git a/tests/Monolog/Handler/RotatingFileHandlerTest.php b/tests/Monolog/Handler/RotatingFileHandlerTest.php
index f4cefda1..96e6dff4 100644
--- a/tests/Monolog/Handler/RotatingFileHandlerTest.php
+++ b/tests/Monolog/Handler/RotatingFileHandlerTest.php
@@ -12,19 +12,52 @@
 namespace Monolog\Handler;
 
 use Monolog\TestCase;
+use PHPUnit_Framework_Error_Deprecated;
 
 /**
  * @covers Monolog\Handler\RotatingFileHandler
  */
 class RotatingFileHandlerTest extends TestCase
 {
+    /**
+     * This var should be private but then the anonymous function
+     * in the `setUp` method won't be able to set it. `$this` cant't
+     * be used in the anonymous function in `setUp` because PHP 5.3
+     * does not support it.
+     */
+    public $lastError;
+
     public function setUp()
     {
         $dir = __DIR__.'/Fixtures';
         chmod($dir, 0777);
         if (!is_writable($dir)) {
-            $this->markTestSkipped($dir.' must be writeable to test the RotatingFileHandler.');
+            $this->markTestSkipped($dir.' must be writable to test the RotatingFileHandler.');
         }
+        $this->lastError = null;
+        $self = $this;
+        // workaround with &$self used for PHP 5.3
+        set_error_handler(function($code, $message) use (&$self) {
+            $self->lastError = array(
+                'code' => $code,
+                'message' => $message,
+            );
+        });
+    }
+
+    private function assertErrorWasTriggered($code, $message)
+    {
+        if (empty($this->lastError)) {
+            $this->fail(
+                sprintf(
+                    'Failed asserting that error with code `%d` and message `%s` was triggered',
+                    $code,
+                    $message
+                )
+            );
+        }
+        $this->assertEquals($code, $this->lastError['code'], sprintf('Expected an error with code %d to be triggered, got `%s` instead', $code, $this->lastError['code']));
+        $this->assertEquals($message, $this->lastError['message'], sprintf('Expected an error with message `%d` to be triggered, got `%s` instead', $message, $this->lastError['message']));
     }
 
     public function testRotationCreatesNewFile()
@@ -43,14 +76,14 @@ class RotatingFileHandlerTest extends TestCase
     /**
      * @dataProvider rotationTests
      */
-    public function testRotation($createFile)
+    public function testRotation($createFile, $dateFormat, $timeCallback)
     {
-        touch($old1 = __DIR__.'/Fixtures/foo-'.date('Y-m-d', time() - 86400).'.rot');
-        touch($old2 = __DIR__.'/Fixtures/foo-'.date('Y-m-d', time() - 86400 * 2).'.rot');
-        touch($old3 = __DIR__.'/Fixtures/foo-'.date('Y-m-d', time() - 86400 * 3).'.rot');
-        touch($old4 = __DIR__.'/Fixtures/foo-'.date('Y-m-d', time() - 86400 * 4).'.rot');
+        touch($old1 = __DIR__.'/Fixtures/foo-'.date($dateFormat, $timeCallback(-1)).'.rot');
+        touch($old2 = __DIR__.'/Fixtures/foo-'.date($dateFormat, $timeCallback(-2)).'.rot');
+        touch($old3 = __DIR__.'/Fixtures/foo-'.date($dateFormat, $timeCallback(-3)).'.rot');
+        touch($old4 = __DIR__.'/Fixtures/foo-'.date($dateFormat, $timeCallback(-4)).'.rot');
 
-        $log = __DIR__.'/Fixtures/foo-'.date('Y-m-d').'.rot';
+        $log = __DIR__.'/Fixtures/foo-'.date($dateFormat).'.rot';
 
         if ($createFile) {
             touch($log);
@@ -58,6 +91,7 @@ class RotatingFileHandlerTest extends TestCase
 
         $handler = new RotatingFileHandler(__DIR__.'/Fixtures/foo.rot', 2);
         $handler->setFormatter($this->getIdentityFormatter());
+        $handler->setFilenameFormat('{filename}-{date}', $dateFormat);
         $handler->handle($this->getRecord());
 
         $handler->close();
@@ -72,11 +106,88 @@ class RotatingFileHandlerTest extends TestCase
 
     public function rotationTests()
     {
+        $now = time();
+        $dayCallback = function($ago) use ($now) {
+            return $now + 86400 * $ago;
+        };
+        $monthCallback = function($ago) {
+            return gmmktime(0, 0, 0, date('n') + $ago, date('d'), date('Y'));
+        };
+        $yearCallback = function($ago) {
+            return gmmktime(0, 0, 0, date('n'), date('d'), date('Y') + $ago);
+        };
+
         return array(
             'Rotation is triggered when the file of the current day is not present'
-                => array(true),
-            'Rotation is not triggered when the file is already present'
-                => array(false),
+                => array(true, RotatingFileHandler::FILE_PER_DAY, $dayCallback),
+            'Rotation is not triggered when the file of the current day is already present'
+                => array(false, RotatingFileHandler::FILE_PER_DAY, $dayCallback),
+
+            'Rotation is triggered when the file of the current month is not present'
+                => array(true, RotatingFileHandler::FILE_PER_MONTH, $monthCallback),
+            'Rotation is not triggered when the file of the current month is already present'
+                => array(false, RotatingFileHandler::FILE_PER_MONTH, $monthCallback),
+
+            'Rotation is triggered when the file of the current year is not present'
+                => array(true, RotatingFileHandler::FILE_PER_YEAR, $yearCallback),
+            'Rotation is not triggered when the file of the current year is already present'
+                => array(false, RotatingFileHandler::FILE_PER_YEAR, $yearCallback),
+        );
+    }
+
+    /**
+     * @dataProvider dateFormatProvider
+     */
+    public function testAllowOnlyFixedDefinedDateFormats($dateFormat, $valid)
+    {
+        $handler = new RotatingFileHandler(__DIR__.'/Fixtures/foo.rot', 2);
+        $handler->setFilenameFormat('{filename}-{date}', $dateFormat);
+        if (!$valid) {
+            $this->assertErrorWasTriggered(
+                E_USER_DEPRECATED,
+                'Invalid date format - format should be one of '.
+                'RotatingFileHandler::FILE_PER_DAY, RotatingFileHandler::FILE_PER_MONTH '.
+                'or RotatingFileHandler::FILE_PER_YEAR.'
+            );
+        }
+    }
+
+    public function dateFormatProvider()
+    {
+        return array(
+            array(RotatingFileHandler::FILE_PER_DAY, true),
+            array(RotatingFileHandler::FILE_PER_MONTH, true),
+            array(RotatingFileHandler::FILE_PER_YEAR, true),
+            array('m-d-Y', false),
+            array('Y-m-d-h-i', false)
+        );
+    }
+
+    /**
+     * @dataProvider filenameFormatProvider
+     */
+    public function testDisallowFilenameFormatsWithoutDate($filenameFormat, $valid)
+    {
+        $handler = new RotatingFileHandler(__DIR__.'/Fixtures/foo.rot', 2);
+        $handler->setFilenameFormat($filenameFormat, RotatingFileHandler::FILE_PER_DAY);
+        if (!$valid) {
+            $this->assertErrorWasTriggered(
+                E_USER_DEPRECATED,
+                'Invalid filename format - format should contain at least `{date}`, because otherwise rotating is impossible.'
+            );
+        }
+    }
+
+    public function filenameFormatProvider()
+    {
+        return array(
+            array('{filename}', false),
+            array('{filename}-{date}', true),
+            array('{date}', true),
+            array('foobar-{date}', true),
+            array('foo-{date}-bar', true),
+            array('{date}-foobar', true),
+            array('foobar', false),
         );
     }
 
@@ -95,5 +206,6 @@ class RotatingFileHandlerTest extends TestCase
         foreach (glob(__DIR__.'/Fixtures/*.rot') as $file) {
             unlink($file);
         }
+        restore_error_handler();
     }
 }