diff --git a/src/calibre/devices/__init__.py b/src/calibre/devices/__init__.py
index 5c7da00861..37ec55c149 100644
--- a/src/calibre/devices/__init__.py
+++ b/src/calibre/devices/__init__.py
@@ -56,6 +56,12 @@ def get_connected_device():
     return dev
 
 def debug(ioreg_to_tmp=False, buf=None, plugins=None):
+    '''
+    If plugins is None, then this method calls startup and shutdown on the
+    device plugins. So if you are using it in a context where startup could
+    already have been called (for example in the main GUI), pass in the list of
+    device plugins as the plugins parameter.
+    '''
     import textwrap
     from calibre.customize.ui import device_plugins
     from calibre.devices.scanner import DeviceScanner, win_pnp_drives
diff --git a/src/calibre/devices/mtp/base.py b/src/calibre/devices/mtp/base.py
index f29f525b30..7f20b70b39 100644
--- a/src/calibre/devices/mtp/base.py
+++ b/src/calibre/devices/mtp/base.py
@@ -7,8 +7,17 @@ __license__   = 'GPL v3'
 __copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
+from functools import wraps
+
 from calibre.devices.interface import DevicePlugin
 
+def synchronous(func):
+    @wraps(func)
+    def synchronizer(self, *args, **kwargs):
+        with self.lock:
+            return func(self, *args, **kwargs)
+    return synchronizer
+
 class MTPDeviceBase(DevicePlugin):
     name = 'SmartDevice App Interface'
     gui_name = _('MTP Device')
diff --git a/src/calibre/devices/mtp/unix/driver.py b/src/calibre/devices/mtp/unix/driver.py
index 86f2c9b573..d8cd7ee01d 100644
--- a/src/calibre/devices/mtp/unix/driver.py
+++ b/src/calibre/devices/mtp/unix/driver.py
@@ -9,23 +9,15 @@ __docformat__ = 'restructuredtext en'
 
 import time, operator
 from threading import RLock
-from functools import wraps
 from itertools import chain
 from collections import deque, OrderedDict
 from io import BytesIO
 
 from calibre import prints
 from calibre.devices.errors import OpenFailed
-from calibre.devices.mtp.base import MTPDeviceBase
+from calibre.devices.mtp.base import MTPDeviceBase, synchronous
 from calibre.devices.mtp.unix.detect import MTPDetect
 
-def synchronous(func):
-    @wraps(func)
-    def synchronizer(self, *args, **kwargs):
-        with self.lock:
-            return func(self, *args, **kwargs)
-    return synchronizer
-
 class FilesystemCache(object):
 
     def __init__(self, files, folders):
@@ -190,15 +182,19 @@ class MTP_DEVICE(MTPDeviceBase):
         if len(storage) > 2:
             self._cardb_id = storage[2]['id']
 
-        files, errs = self.dev.get_filelist(self)
-        if errs and not files:
-            raise OpenFailed('Failed to read files from device. Underlying errors:\n'
-                    +self.format_errorstack(errs))
-        folders, errs = self.dev.get_folderlist()
-        if errs and not folders:
-            raise OpenFailed('Failed to read folders from device. Underlying errors:\n'
-                    +self.format_errorstack(errs))
-        self.filesystem_cache = FilesystemCache(files, folders)
+        try:
+            files, errs = self.dev.get_filelist(self)
+            if errs and not files:
+                raise OpenFailed('Failed to read files from device. Underlying errors:\n'
+                        +self.format_errorstack(errs))
+            folders, errs = self.dev.get_folderlist()
+            if errs and not folders:
+                raise OpenFailed('Failed to read folders from device. Underlying errors:\n'
+                        +self.format_errorstack(errs))
+            self.filesystem_cache = FilesystemCache(files, folders)
+        except:
+            self.dev = self._main_id = self._carda_id = self._cardb_id = None
+            raise
 
     @synchronous
     def get_device_information(self, end_session=True):