diff --git a/src/calibre/gui2/actions/similar_books.py b/src/calibre/gui2/actions/similar_books.py
index 5b82236150..e9015aa29b 100644
--- a/src/calibre/gui2/actions/similar_books.py
+++ b/src/calibre/gui2/actions/similar_books.py
@@ -43,7 +43,8 @@ class SimilarBooksAction(InterfaceAction):
         row = idx.row()
 
         # Get the parameters for this search
-        col = db.prefs['similar_' + typ + '_search_key']
+        key = 'similar_' + typ + '_search_key'
+        col = db.prefs[key]
         match = db.prefs['similar_' + typ + '_match_kind']
         if match == 'match_all':
             join = ' and '
@@ -70,7 +71,11 @@ class SimilarBooksAction(InterfaceAction):
                 else:
                     val.add(v)
         else:
-            # Get the value of the requested field. Can be a list or a simple val
+            # Get the value of the requested field. Can be a list or a simple
+            # val. It is possible that col no longer exists, in which case fall
+            # back to the default
+            if col not in mi:
+                col = db.prefs.defaults[key]
             val = mi.get(col, None)
         if not val:
             return
diff --git a/src/calibre/gui2/preferences/search.py b/src/calibre/gui2/preferences/search.py
index c270e54b78..5f4d7d94f9 100644
--- a/src/calibre/gui2/preferences/search.py
+++ b/src/calibre/gui2/preferences/search.py
@@ -133,7 +133,15 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         if dex >= 0:
             field.setCurrentIndex(dex)
         else:
-            field.setCurrentIndex(0)
+            # The field no longer exists. Try the default
+            dex = field.findText(self.db.prefs.defaults[name])
+            if dex >= 0:
+                field.setCurrentIndex(dex)
+            else:
+                # The default doesn't exist! Pick the first field in the list
+                field.setCurrentIndex(0)
+            # Emit a changed signal after all the other events have been processed
+            QTimer.singleShot(0, self.changed_signal.emit)
         field.blockSignals(False)
 
     def something_changed(self, dex):