Sr2RuO4 is a prototypical unconventional superconductor, but the superconducting symmetries of the bulk and surface states in single crystals remains controversial. Solving this problem is impeded by the challenge of producing thin-films of Sr2RuO4 free of defects and impurities which annihilate the superconductivity. Here, we report the reliable growth of superconducting Sr2RuO4 thin-films by pulsed laser deposition and identify the universal material properties that are destructive to the superconducting state. We demonstrate that careful control of the starting material is essential to achieve superconductivity as well as the use of a single crystal target of Sr3Ru2O7. By systematically varying the Sr2RuO4 film thickness, we identify mosaic twist as the key in-plane defect that suppresses superconductivity. These results are central to the development of our understanding of unconventional superconductivity.