diff --git a/django/utils/encoding.py b/django/utils/encoding.py
index c54e67610f..dbd2c7a211 100644
--- a/django/utils/encoding.py
+++ b/django/utils/encoding.py
@@ -48,7 +48,19 @@ def force_unicode(s, encoding='utf-8', strings_only=False, errors='strict'):
             if hasattr(s, '__unicode__'):
                 s = unicode(s)
             else:
-                s = unicode(str(s), encoding, errors)
+                try:
+                    s = unicode(str(s), encoding, errors)
+                except UnicodeEncodeError:
+                    if not isinstance(s, Exception):
+                        raise
+                    # If we get to here, the caller has passed in an Exception
+                    # subclass populated with non-ASCII data without special
+                    # handling to display as a string. We need to handle this
+                    # without raising a further exception. We do an
+                    # approximation to what the Exception's standard str()
+                    # output should be.
+                    s = ' '.join([force_unicode(arg, encoding, strings_only,
+                            errors) for arg in s])
         elif not isinstance(s, unicode):
             # Note: We use .decode() here, instead of unicode(s, encoding,
             # errors), so that if s is a SafeString, it ends up being a
@@ -72,6 +84,12 @@ def smart_str(s, encoding='utf-8', strings_only=False, errors='strict'):
         try:
             return str(s)
         except UnicodeEncodeError:
+            if isinstance(s, Exception):
+                # An Exception subclass containing non-ASCII data that doesn't
+                # know how to print itself properly. We shouldn't raise a
+                # further exception.
+                return ' '.join([smart_str(arg, encoding, strings_only,
+                        errors) for arg in s])
             return unicode(s).encode(encoding, errors)
     elif isinstance(s, unicode):
         return s.encode(encoding, errors)