diff -r 211472ab15c8 -r a8c1ea390400 cubicweb/_exceptions.py
--- a/cubicweb/_exceptions.py	Thu Mar 14 14:45:35 2019 +0100
+++ b/cubicweb/_exceptions.py	Thu Mar 14 12:08:37 2019 +0100
@@ -102,14 +102,6 @@
         cstr = self.session.find('CWUniqueTogetherConstraint', name=cstrname).one()
         return sorted(rtype.name for rtype in cstr.relations)
 
-    @cachedproperty
-    def args(self):
-        warn('[3.18] UniqueTogetherError.args is deprecated, just use '
-             'the .rtypes accessor.',
-             DeprecationWarning)
-        # the first argument, etype, is never used and was never garanteed anyway
-        return None, self.rtypes
-
 
 class ViolatedConstraint(RepositoryError):
     def __init__(self, cnx, cstrname):