diff --git a/qutebrowser/browser/webkit/network/webkitqutescheme.py b/qutebrowser/browser/webkit/network/webkitqutescheme.py
index 4ae68d3d7..cb4c68d97 100644
--- a/qutebrowser/browser/webkit/network/webkitqutescheme.py
+++ b/qutebrowser/browser/webkit/network/webkitqutescheme.py
@@ -83,7 +83,7 @@ class JSBridge(QObject):
         try:
             objreg.get('config').set('conf', sectname, optname, value)
         except (configexc.Error, configparser.Error) as e:
-            message.error(e)
+            message.error(str(e))
 
 
 @qutescheme.add_handler('settings', backend=usertypes.Backend.QtWebKit)
diff --git a/qutebrowser/commands/runners.py b/qutebrowser/commands/runners.py
index c96d809ad..8569342ec 100644
--- a/qutebrowser/commands/runners.py
+++ b/qutebrowser/commands/runners.py
@@ -320,7 +320,7 @@ class CommandRunner(QObject):
         try:
             self.run(text, count)
         except (cmdexc.CommandMetaError, cmdexc.CommandError) as e:
-            message.error(e, stack=traceback.format_exc())
+            message.error(str(e), stack=traceback.format_exc())
 
     @pyqtSlot(str, int)
     def run_safely_init(self, text, count=None):
@@ -332,4 +332,4 @@ class CommandRunner(QObject):
         try:
             self.run(text, count)
         except (cmdexc.CommandMetaError, cmdexc.CommandError) as e:
-            message.error(e, stack=traceback.format_exc())
+            message.error(str(e), stack=traceback.format_exc())