Fuzzy dark matter fails to explain the dark matter cores

Ultrafaint dwarf galaxies (UFDs) are ideal for studying dark matter (DM) due to minimal baryonic effects. UFD observations suggest cored DM profiles. We find that the core radius -- stellar mass scaling predicted by fuzzy dark matter (FDM) is at $6.1\sigma$ tension with UFD observations. Combining observations from 27 UFDs, the required FDM mass $m_a = 3.2_{-0.6}^{+0.8}\times 10^{-21}\,{\rm eV}$ is also in conflict with existing Lyman-$\alpha$ bounds. Our results suggest that FDM cannot provide a consistent explanation for DM cores and imply $m_a > 2.2\times 10^{-21}\,{\rm eV}$ at to $2\sigma$ CL.