diff --git a/coco/sftp.py b/coco/sftp.py
index b835a25c5cef5be3918e4613b1457a9ea58fe493..629b3fe905e1517448a1fb6fd191ddda2d4bc73c 100644
--- a/coco/sftp.py
+++ b/coco/sftp.py
@@ -160,7 +160,11 @@ class SFTPServer(paramiko.SFTPServerInterface):
             return attr
         else:
             sftp = self.get_host_sftp(host, su)
-            return sftp.stat(rpath)
+            try:
+                stat = sftp.stat(rpath)
+                return stat
+            except FileNotFoundError as e:
+                return paramiko.SFTPServer.convert_errno(e.errno)
 
     def lstat(self, path):
         host, su, rpath = self.parse_path(path)
diff --git a/requirements/requirements.txt b/requirements/requirements.txt
index ce1eb73f8f2a599904a55a10c4a0b1430e7d0b9e..dc6f7288c89a71ad1f2bdbd4a98675f59a386b16 100644
--- a/requirements/requirements.txt
+++ b/requirements/requirements.txt
@@ -8,7 +8,7 @@ cffi==1.11.2
 chardet==3.0.4
 click==6.7
 crcmod==1.7
-cryptography==2.1.4
+cryptography==2.3.1
 docutils==0.14
 dotmap==1.2.20
 elasticsearch==6.1.1
@@ -40,5 +40,5 @@ six==1.11.0
 tornado==4.5.2
 urllib3==1.22
 wcwidth==0.1.7
-eventlet==0.22.1
+eventlet==0.24.1
 Werkzeug==0.14.1