if one recalls that in the usual type IIB construction, supersymmetric flux configurations have an imaginary self-dual (ISD) property and therefore lead to a positive definite contribution to the D3-brane tadpole. As a consequence, there should not be any supersymmetric runaway direction in flux space which is not constrained by the tadpole. The reason for the unexpected existence of a runaway direction in flux space is an unusual prefactor in the Kähler potential for the dilaton. This prefactor is peculiar to the [*non-geometric models*]{} we consider here, and is predicted by mirror symmetry as we explain in some detail. Supersymmetric fluxes in the non-geometric type IIB models are not constrained to be ISD.

This paper is organized as follows. In section 2 we review some of the relevant formulas of the type IIB model constructed in [@BVW] that will be needed in the later sections. Due to its importance in connection to the existence of strong coupling solutions, we will elaborate the non-renormalization theorem presented in [@BVW] in some more detail. In section 3 we present the equations that constrain weak coupling type IIB flux vacua. In section 4 it is shown that AdS type weak coupling solutions can be 