diff --git a/cps/kobo_auth.py b/cps/kobo_auth.py
index 9865b993..ea9b71b1 100644
--- a/cps/kobo_auth.py
+++ b/cps/kobo_auth.py
@@ -107,7 +107,7 @@ def generate_auth_token(user_id):
 
     for book in books:
         formats = [data.format for data in book.data]
-        if not 'KEPUB' in formats and config.config_kepubifypath and 'EPUB' in formats:
+        if 'KEPUB' not in formats and config.config_kepubifypath and 'EPUB' in formats:
             helper.convert_book_format(book.id, config.config_calibre_dir, 'EPUB', 'KEPUB', current_user.name)
 
     return render_title_template(
diff --git a/cps/tasks/convert.py b/cps/tasks/convert.py
index a9f0f055..48fd528e 100755
--- a/cps/tasks/convert.py
+++ b/cps/tasks/convert.py
@@ -188,6 +188,8 @@ class TaskConvert(CalibreTask):
         log.info("ebook converter failed with error while converting book")
         if not error_message:
             error_message = N_('Ebook converter failed with unknown error')
+        else:
+            log.error(error_message)
         self._handleError(error_message)
         return
 
@@ -273,7 +275,10 @@ class TaskConvert(CalibreTask):
         return N_("Convert")
 
     def __str__(self):
-        return "Convert {} {}".format(self.book_id, self.ereader_mail)
+        if self.ereader_mail:
+            return "Convert {} {}".format(self.book_id, self.ereader_mail)
+        else:
+            return "Convert {}".format(self.book_id)
 
     @property
     def is_cancellable(self):