A significant barrier to the commercialization of solution-processed perovskite solar cells (PSCs) is the chemical instability of the components in precursor solutions under ambient conditions. This instability leads to solution aging, which subsequently diminishes the quality and reproducibility of the resulting PSCs. Inspired by recent published works, which focused on the deprotonation of organic cations, the oxidation of iodide, and the formation of undesired byproducts, we here systematically summarize and provide an outlook on the research directions and perspectives of the origin of precursor solution aging and countermeasures, such as using stabilizing additives, redox shuttles, Schiff base reactions, and green solvents. We are aiming to provide insight into potential paths for achieving reproducible and efficient PSCs with high operational stability.