Abstract: I will review in a pedagogical manner the vanilla models (KKLT) that have lead to the conjecture of a string theory &quot;landscape&quot; of meta-stable de Sitter vacua. A central role is played by the so called uplifting anti-branes that break the supersymmetry of the AdS vacua and lift the cosmological constant to a positive value. In the last years it has become clear that the supergravity description of this process reveals problematic features such as unwanted singularities. Although this is a technical topic I will review it in a non technical fashion with an emphasis on the physics behind it. I will advocate the point of view that these singularities are easy to interpret and signal the instability of the vacuum. If correct this invalidates the original motivation for the landscape conjecture.<br><br>