Stomach ulcers are usually caused by Helicobacter pylori (H. pylori) bacteria or non-steroidal anti-inflammatory drugs (NSAIDs). These can break down the stomach's defence against the acid it produces to digest food. The stomach lining then becomes damaged causing an ulcer to form
Because pylori bacteria causes stomach ulcers, that sores the lining of the stomach, damaging the acid and making it vulnerable. If this acid is not contained, you will die since the stomach has special protection to keep it out in the first place. You will also leak out your intestines, so there's obviously no way you would survive.