diff --git a/weboob/backends/aum/pages/contact_thread.py b/weboob/backends/aum/pages/contact_thread.py
index 4273edcb..238390b8 100644
--- a/weboob/backends/aum/pages/contact_thread.py
+++ b/weboob/backends/aum/pages/contact_thread.py
@@ -257,14 +257,14 @@ class ContactThreadPage(PageBase):
 
             self.browser.submit()  # submit current form
         except FormNotFoundError, e:
-            error = 'Unknown error (%s)' % e
+            error = u'Unknown error (%s)' % e
             p_list = self.document.getElementsByTagName('p')
             for p in p_list:
                 if p.hasAttribute('align') and p.getAttribute('align') == 'center':
                     error = p.firstChild.data
                     break
 
-            raise AdopteCantPostMail(error)
+            raise AdopteCantPostMail(error.encode('utf-8'))
 
 
     """
diff --git a/weboob/tools/misc.py b/weboob/tools/misc.py
index e15eb13e..4f7b6fa4 100644
--- a/weboob/tools/misc.py
+++ b/weboob/tools/misc.py
@@ -38,10 +38,7 @@ def to_unicode(text):
     if isinstance(text, unicode):
         return text
     if not isinstance(text, str):
-        try:
-            text = str(text)
-        except UnicodeError:
-            pass
+        text = str(text)
     try:
         return unicode(text, 'utf-8')
     except UnicodeError: