--- a/cubicweb/req.py	Tue Jan 14 09:43:02 2020 +0100
+++ b/cubicweb/req.py	Tue Jan 14 17:38:11 2020 +0100
@@ -34,10 +34,6 @@
 CACHE_REGISTRY = {}
 
 
-class FindEntityError(Exception):
-    """raised when find_one_entity() can not return one and only one entity"""
-
-
 class Cache(dict):
     def __init__(self):
         super(Cache, self).__init__()

--- a/doc/api/req.rst	Tue Jan 14 09:43:02 2020 +0100
+++ b/doc/api/req.rst	Tue Jan 14 17:38:11 2020 +0100
@@ -5,7 +5,5 @@
 
 .. automodule:: cubicweb.req
 
-    .. autoexception:: FindEntityError
-
     .. autoclass:: RequestSessionBase
         :members: