diff --git a/src/calibre/gui2/preferences/misc.py b/src/calibre/gui2/preferences/misc.py
index eae79fdfc0..e749a6fb98 100644
--- a/src/calibre/gui2/preferences/misc.py
+++ b/src/calibre/gui2/preferences/misc.py
@@ -88,10 +88,16 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         r('enforce_cpu_limit', config, restart_required=True)
         self.device_detection_button.clicked.connect(self.debug_device_detection)
         self.compact_button.clicked.connect(self.compact)
+        self.button_all_books_dirty.clicked.connect(self.mark_dirty)
         self.button_open_config_dir.clicked.connect(self.open_config_dir)
         self.button_osx_symlinks.clicked.connect(self.create_symlinks)
         self.button_osx_symlinks.setVisible(isosx)
 
+    def mark_dirty(self):
+        db = self.gui.library_view.model().db
+        ids = [id for id in db.data.iterallids()]
+        db.dirtied(ids)
+
     def debug_device_detection(self, *args):
         from calibre.gui2.preferences.device_debug import DebugDevice
         d = DebugDevice(self)
diff --git a/src/calibre/gui2/preferences/misc.ui b/src/calibre/gui2/preferences/misc.ui
index f8582a3675..573c61aba5 100644
--- a/src/calibre/gui2/preferences/misc.ui
+++ b/src/calibre/gui2/preferences/misc.ui
@@ -124,7 +124,14 @@
      </property>
     </widget>
    </item>
-   <item row="10" column="0">
+   <item row="10" column="0" colspan="2">
+    <widget class="QPushButton" name="button_all_books_dirty">
+     <property name="text">
+      <string>Force saving metadata of all books</string>
+     </property>
+    </widget>
+   </item>
+   <item row="20" column="0">
     <spacer name="verticalSpacer_9">
      <property name="orientation">
       <enum>Qt::Vertical</enum>
@@ -132,7 +139,7 @@
      <property name="sizeHint" stdset="0">
       <size>
        <width>20</width>
-       <height>18</height>
+       <height>1000</height>
       </size>
      </property>
     </spacer>
diff --git a/src/calibre/library/caches.py b/src/calibre/library/caches.py
index cdf0c1fce6..9d6f87324f 100644
--- a/src/calibre/library/caches.py
+++ b/src/calibre/library/caches.py
@@ -44,6 +44,7 @@ class MetadataBackup(Thread): # {{{
         self.keep_running = False
 
     def run(self):
+        import traceback
         while self.keep_running:
             try:
                 time.sleep(0.5) # Limit to two per second
@@ -53,11 +54,11 @@ class MetadataBackup(Thread): # {{{
             except:
                 # Happens during interpreter shutdown
                 break
+
             try:
                 path, mi = self.get_metadata_for_dump(id_)
             except:
                 prints('Failed to get backup metadata for id:', id_, 'once')
-                import traceback
                 traceback.print_exc()
                 time.sleep(2)
                 try:
@@ -67,6 +68,10 @@ class MetadataBackup(Thread): # {{{
                     traceback.print_exc()
                     continue
 
+            if mi is None:
+                self.clear_dirtied([id_])
+                continue
+
             # Give the GUI thread a chance to do something. Python threads don't
             # have priorities, so this thread would naturally keep the processor
             # until some scheduling event happens. The sleep makes such an event
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index 0943c86e43..6f628d8454 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -657,8 +657,11 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         self.dirtied(book_ids)
 
     def get_metadata_for_dump(self, idx):
-        path = os.path.join(self.abspath(idx, index_is_id=True), 'metadata.opf')
-        mi = self.get_metadata(idx, index_is_id=True)
+        try:
+            path = os.path.join(self.abspath(idx, index_is_id=True), 'metadata.opf')
+            mi = self.get_metadata(idx, index_is_id=True)
+        except:
+            return ((None, None))
         return ((path, mi))
 
     def get_metadata(self, idx, index_is_id=False, get_cover=False):