diff --git a/src/caosdb/exceptions.py b/src/caosdb/exceptions.py
index 45c4570b4227031a35a486b86ea65535ff105852..20c5f7c97de3f4e3fe185b211da07d190ffbba04 100644
--- a/src/caosdb/exceptions.py
+++ b/src/caosdb/exceptions.py
@@ -72,6 +72,7 @@ class ServerErrorException(CaosDBException):
         xml = etree.fromstring(body)
         error = xml.xpath('/Response/Error')[0]
         msg = error.get("description")
+
         if error.text is not None:
             msg = msg + "\n\n" + error.text
         CaosDBException.__init__(self, msg)
@@ -114,15 +115,18 @@ class TransactionError(CaosDBException):
     def _calc_bases(self):
         types = dict()
         # collect each class once
+
         for err in self.errors:
             types[id(type(err))] = type(err)
         # delete redundant super classes
+
         if len(types.values()) > 1:
             # remove TransactionError
             try:
                 del types[id(TransactionError)]
             except KeyError:
                 pass
+
         if len(types.values()) > 1:
             # remove EntityError
             try:
@@ -131,10 +135,13 @@ class TransactionError(CaosDBException):
                 pass
 
         ret = ()
+
         for t in types.values():
             ret += (t,)
+
         if ret == ():
             ret = (type(self),)
+
         return ret
 
     def __init__(self, container=None, error=None, msg=None):
@@ -145,6 +152,7 @@ class TransactionError(CaosDBException):
 
     def print_errs(self):
         print(self)
+
         for err in self.errors:
             err.print_errs()
 
@@ -158,6 +166,7 @@ class TransactionError(CaosDBException):
         newinstance = newtype(container=self.container, error=self.msg)
         newinstance.errors = self.errors
         newinstance.get_entities = self.get_entities
+
         return newinstance
 
     def get_container(self):
@@ -165,6 +174,7 @@ class TransactionError(CaosDBException):
         @return: The container that raised this TransactionError during the last
         transaction.
         '''
+
         return self.container
 
     def add_error(self, error):
@@ -177,12 +187,15 @@ class TransactionError(CaosDBException):
 
         @return: self.
         """
+
         if hasattr(error, "__iter__"):
             for e in error:
                 self.add_error(e)
+
             return self
         elif isinstance(error, TransactionError):
             self.errors.append(error)
+
             return self
         else:
             raise TypeError(
@@ -192,17 +205,21 @@ class TransactionError(CaosDBException):
         '''
         @return: A list of all EntityError objects.
         '''
+
         if hasattr(self, 'errors'):
             return self.errors
+
         return None
 
     def _repr_reasons(self, indent):
         if self.get_errors() is not None and len(self.get_errors()) > 0:
             ret = "\n" + indent + "    +--| REASONS |--"
+
             for c in self.get_errors():
                 ret += '\n' + indent + '    |  -> ' + \
                     c.__str__(indent=indent + '    |')
             ret += "\n" + indent + "    +----------------"
+
             return ret
         else:
             return ''
@@ -214,6 +231,7 @@ class TransactionError(CaosDBException):
     def __str__(self, indent=''):
         ret = self._repr_head(indent=indent)
         ret += self._repr_reasons(indent=indent)
+
         return ret
 
     def __repr__(self):
@@ -224,8 +242,10 @@ class TransactionError(CaosDBException):
         @return: A list of all Entity objects with errors.
         '''
         ret = []
+
         if hasattr(self, 'get_entity') and self.get_entity() is not None:
             ret.append(self.get_entity())
+
         for error in self.errors:
             if hasattr(error, 'get_entity'):
                 if error.get_entity() not in ret:
@@ -247,10 +267,12 @@ class EntityError(TransactionError):
         if len(t) > 1:
             ret = ()
             '''remove EntityError'''
+
             for i in range(len(t)):
                 if t[i] != EntityError:
                     ret += (t[i],)
             t = ret
+
         return t
 
     def _convert(self):
@@ -260,12 +282,14 @@ class EntityError(TransactionError):
         setattr(newinstance, 'msg', self.msg)
         setattr(newinstance, 'errors', self.errors)
         setattr(newinstance, 'container', self.container)
+
         return newinstance
 
     def __init__(self, error=None, container=None, entity=None):
         TransactionError.__init__(self, container=container)
         self.error = error
         self.entity = entity
+
         if error is not None and hasattr(error, "encode"):
             self.msg = error
         elif error is not None and hasattr(error, 'description'):
@@ -279,8 +303,10 @@ class EntityError(TransactionError):
         '''
         @return: The entity that caused this error.
         '''
+
         if hasattr(self, 'entity'):
             return self.entity
+
         return None
 
     @property
@@ -294,6 +320,7 @@ class EntityError(TransactionError):
         '''
         @return: Error Message object of this Error.
         '''
+
         return self.error
 
     def _repr_head(self, indent):