Debugger used to work on 2.4

PyCharm debugger used to work using Python 2.4.4.  I do not know what happened, but it is no longer working.

It is now complaining syntax not supported in 2.4:

  File "C:\Program Files (x86)\JetBrains\PyCharm Community Edition 2016.2.3\helpers\pydev\_pydevd_bundle\pydevd_vars.py", line 601
    fmt = format if (dtype == 'f' and format) else default_format(dtype)
                  ^
SyntaxError: invalid syntax

Python version 2.4 does not support this syntax

I have updated my PyCharm a lot so I no longer know which version supports 2.4 in debugger.

Any help will be much appreciated.  I cannot upgrade my Python since production uses 2.4.