diff --git a/system/libraries/Cache/drivers/Cache_apc.php b/system/libraries/Cache/drivers/Cache_apc.php
index 127a220..a84e7d2 100644
--- a/system/libraries/Cache/drivers/Cache_apc.php
+++ b/system/libraries/Cache/drivers/Cache_apc.php
@@ -150,7 +150,7 @@
 	{
 		if ( ! extension_loaded('apc') OR ! (bool) @ini_get('apc.enabled'))
 		{
-			log_message('error', 'The APC PHP extension must be loaded to use APC Cache.');
+			log_message('debug', 'The APC PHP extension must be loaded to use APC Cache.');
 			return FALSE;
 		}
 
diff --git a/system/libraries/Cache/drivers/Cache_memcached.php b/system/libraries/Cache/drivers/Cache_memcached.php
index 35d9104..d2a3a48 100644
--- a/system/libraries/Cache/drivers/Cache_memcached.php
+++ b/system/libraries/Cache/drivers/Cache_memcached.php
@@ -240,7 +240,7 @@
 	{
 		if ( ! extension_loaded('memcached') && ! extension_loaded('memcache'))
 		{
-			log_message('error', 'The Memcached Extension must be loaded to use Memcached Cache.');
+			log_message('debug', 'The Memcached Extension must be loaded to use Memcached Cache.');
 			return FALSE;
 		}
 
diff --git a/system/libraries/Cache/drivers/Cache_redis.php b/system/libraries/Cache/drivers/Cache_redis.php
index 484f284..40823fc 100644
--- a/system/libraries/Cache/drivers/Cache_redis.php
+++ b/system/libraries/Cache/drivers/Cache_redis.php
@@ -168,7 +168,7 @@
 		}
 		else
 		{
-			log_message('error', 'The Redis extension must be loaded to use Redis cache.');
+			log_message('debug', 'The Redis extension must be loaded to use Redis cache.');
 			return FALSE;
 		}
 	}
diff --git a/system/libraries/Cache/drivers/Cache_wincache.php b/system/libraries/Cache/drivers/Cache_wincache.php
index d749978..80d3ac1 100644
--- a/system/libraries/Cache/drivers/Cache_wincache.php
+++ b/system/libraries/Cache/drivers/Cache_wincache.php
@@ -150,7 +150,7 @@
 	{
 		if ( ! extension_loaded('wincache'))
 		{
-			log_message('error', 'The Wincache PHP extension must be loaded to use Wincache Cache.');
+			log_message('debug', 'The Wincache PHP extension must be loaded to use Wincache Cache.');
 			return FALSE;
 		}
 
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 1e463db..4cef0e6 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -311,6 +311,7 @@
       -  Added Wincache driver.
       -  Added Redis driver.
       -  Added a *key_prefix* option for cache IDs.
+      -  Updated driver ``is_supported()`` methods to log at the "debug" level.
 
    -  :doc:`Email library <libraries/email>` changes include: