Electron Cyclotron Resonance Ion Source (ECRIS) demonstrated dramatic improvement in the last decades when operated at high RF power and high frequency. Pioneer research performed in accelerator physics laboratory (LBNL, IMP CAS, MSU, RIKEN) have shown technological limitations that need to be tackled to grant a safe and reliable operation of high frequency ECRIS. This article discusses the challenges of operating ECRIS at high frequency and high RF power. After a brief introduction on ECRIS, the frequency scaling law and the standard magnetic confinement models are presented. The challenges of high power high frequency operation are then reviewed: plasma chamber burning in continuous working operation, wall sputtering in pulse mode operation, high voltage insulator aging, parasitic cold mass heating, high current and magnetic emittance management.