NDSolve::tponly
NDSolveValue::tponly
ParametricNDSolve::tponly
ParametricNDSolveValue::tponly
An error occurs because "Triangularization" is not a valid value for the "SpatialDiscretization" option:
NDSolve[{D[u[x, t], t] == D[u[x, t], x, x], u[x, 0] == Exp[-100 x ^ 2], u[-1, t] == u[1, t]}, u, {x, -1, 1}, {t, 2}, Method -> {"MethodOfLines", "SpatialDiscretization" -> "Triangularization"}]