diff --git a/src/calibre/ebooks/metadata/meta.py b/src/calibre/ebooks/metadata/meta.py
index 3f3cc3e142..d82a2268fa 100644
--- a/src/calibre/ebooks/metadata/meta.py
+++ b/src/calibre/ebooks/metadata/meta.py
@@ -31,7 +31,7 @@ def metadata_from_formats(formats, force_read_metadata=False, pattern=None):
     try:
         return _metadata_from_formats(formats, force_read_metadata, pattern)
     except:
-        mi = metadata_from_filename(list(iter(formats), pattern)[0])
+        mi = metadata_from_filename(list(iter(formats))[0], pat=pattern)
         if not mi.authors:
             mi.authors = [_('Unknown')]
         return mi
diff --git a/src/calibre/gui2/device.py b/src/calibre/gui2/device.py
index e929825245..f3ee0e575e 100644
--- a/src/calibre/gui2/device.py
+++ b/src/calibre/gui2/device.py
@@ -87,7 +87,7 @@ class DeviceJob(BaseJob): # {{{
             self.failed = True
             ex = as_unicode(err)
             self._details = ex + '\n\n' + \
-                traceback.format_exc()
+                force_unicode(traceback.format_exc())
             self.exception = err
         finally:
             self.job_done()