diff -up src/sage/arith/multi_modular.pyx.orig src/sage/arith/multi_modular.pyx --- src/sage/arith/multi_modular.pyx.orig 2016-08-09 07:06:34.166635024 -0400 +++ src/sage/arith/multi_modular.pyx 2016-08-09 07:06:58.190635944 -0400 @@ -171,9 +171,9 @@ cdef class MultiModularBasis_base(object ArithmeticError: The inverse of 6 modulo 10 is not defined. """ if l_bound < 2: - raise ValueError(f"minimum value for lower bound is 2, given: {l_bound}") + raise ValueError("minimum value for lower bound is 2, given: {l_bound}") if u_bound > MAX_MODULUS: - raise ValueError(f"upper bound cannot be greater than {MAX_MODULUS}, given: {u_bound}") + raise ValueError("upper bound cannot be greater than {MAX_MODULUS}, given: {u_bound}") self._l_bound = l_bound self._u_bound = u_bound @@ -232,7 +232,7 @@ cdef class MultiModularBasis_base(object if check: for p in plist: if p > MAX_MODULUS: - raise OverflowError(f"given modulus {p} is larger than {MAX_MODULUS}") + raise OverflowError("given modulus {p} is larger than {MAX_MODULUS}") self._realloc_to_new_count(self.n + len_plist) cdef Py_ssize_t i diff -up src/sage/rings/finite_rings/integer_mod.pyx.orig src/sage/rings/finite_rings/integer_mod.pyx --- src/sage/rings/finite_rings/integer_mod.pyx.orig 2016-08-09 07:06:34.179635024 -0400 +++ src/sage/rings/finite_rings/integer_mod.pyx 2016-08-09 07:07:05.471636223 -0400 @@ -392,7 +392,7 @@ cdef class IntegerMod_abstract(FiniteRin from integer_mod_ring import IntegerModRing R = IntegerModRing(modulus) if (self)._parent._IntegerModRing_generic__order % R.order(): - raise ArithmeticError(f"reduction modulo {modulus!r} not defined") + raise ArithmeticError("reduction modulo {modulus!r} not defined") return R(self) def is_nilpotent(self): diff -up src/sage/structure/parent.pyx.orig src/sage/structure/parent.pyx --- src/sage/structure/parent.pyx.orig 2016-08-09 07:06:34.157635023 -0400 +++ src/sage/structure/parent.pyx 2016-08-09 07:06:50.239635639 -0400 @@ -753,7 +753,7 @@ cdef class Parent(category_object.Catego cdef int init_coerce(self, bint warn=True) except -1: if self._coerce_from_hash is None: if warn: - raise AssertionError(f"unexpected call of init_coerce() for {type(self)}") + raise AssertionError("unexpected call of init_coerce() for {type(self)}") self._initial_coerce_list = [] self._initial_action_list = [] self._initial_convert_list = [] diff -up src/sage/symbolic/ring.pyx.orig src/sage/symbolic/ring.pyx --- src/sage/symbolic/ring.pyx.orig 2016-08-09 07:06:34.173635024 -0400 +++ src/sage/symbolic/ring.pyx 2016-08-09 07:07:01.438636068 -0400 @@ -350,7 +350,7 @@ cdef class SymbolicRing(CommutativeRing) from sage.misc.all import prod return prod([SR(p)**e for p,e in x], SR(x.unit())) else: - raise TypeError(f"unable to convert {x!r} to a symbolic expression") + raise TypeError("unable to convert {x!r} to a symbolic expression") return new_Expression_from_GEx(self, exp)