diff --git a/library/think/session/driver/Memcache.php b/library/think/session/driver/Memcache.php
index 4ef044a4..78320864 100644
--- a/library/think/session/driver/Memcache.php
+++ b/library/think/session/driver/Memcache.php
@@ -79,7 +79,7 @@ class Memcache extends SessionHandler
      */
     public function read($sessID)
     {
-        return $this->handler->get($this->config['session_name'] . $sessID);
+        return (string) $this->handler->get($this->config['session_name'] . $sessID);
     }
 
     /**
diff --git a/library/think/session/driver/Memcached.php b/library/think/session/driver/Memcached.php
index 01d0f1e0..c5df23dc 100644
--- a/library/think/session/driver/Memcached.php
+++ b/library/think/session/driver/Memcached.php
@@ -87,7 +87,7 @@ class Memcached extends SessionHandler
      */
     public function read($sessID)
     {
-        return $this->handler->get($this->config['session_name'] . $sessID);
+        return (string) $this->handler->get($this->config['session_name'] . $sessID);
     }
 
     /**
diff --git a/library/think/session/driver/Redis.php b/library/think/session/driver/Redis.php
index 52f14ab7..b1632f9e 100644
--- a/library/think/session/driver/Redis.php
+++ b/library/think/session/driver/Redis.php
@@ -81,11 +81,11 @@ class Redis extends SessionHandler
      * 读取Session
      * @access public
      * @param string $sessID
-     * @return bool|string
+     * @return string
      */
     public function read($sessID)
     {
-        return $this->handler->get($this->config['session_name'] . $sessID);
+        return (string) $this->handler->get($this->config['session_name'] . $sessID);
     }
 
     /**