# atkpython.exe Stopped Working¶

There could be several reasons for this. First open the output file and check for more detailed error messages. If you are using ATK 2015 the error can be caused by a license error. The error message will be printed in the log file. If you are attempting to run a DFT or a Semi-empirical calculation and get the following error:

 License Error: (Internal: 147 Feature: ATKMaster)