Gekko error “ Results files not found. APM did not find a solution or the server is unreachable”

Question

I follow course on this site: https://apmonitor.com/wiki/index.php/Main/GekkoPythonOptimization

I tried some Gekko script and get same error:

     Successful solution

 ---------------------------------------------------
 Solver         :  APOPT (v1.0)
 Solution time  :   1.429999999527354E-002 sec
 Objective      :    17.0140172891559     
 Successful solution
 ---------------------------------------------------

Traceback (most recent call last):
  File "C:\Python35\lib\site-packages\gekko\gekko.py", line 2005, in solve
    results = byte2str(get_file(self._server,self._model_name,'results.json'))
  File "C:\Python35\lib\site-packages\gekko\apm.py", line 160, in get_file
    f = urllib.request.urlopen(url)
  File "C:\Python35\lib\urllib\request.py", line 163, in urlopen
    return opener.open(url, data, timeout)
  File "C:\Python35\lib\urllib\request.py", line 472, in open
    response = meth(req, response)
  File "C:\Python35\lib\urllib\request.py", line 582, in http_response
    'http', request, response, code, msg, hdrs)
  File "C:\Python35\lib\urllib\request.py", line 510, in error
    return self._call_chain(*args)
  File "C:\Python35\lib\urllib\request.py", line 444, in _call_chain
    result = func(*args)
  File "C:\Python35\lib\urllib\request.py", line 590, in http_error_default
    raise HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 404: Not Found

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:/CIVIL/LePy/le_Gekko1.py", line 44, in <module>
    m.solve()
  File "C:\Python35\lib\site-packages\gekko\gekko.py", line 2022, in solve
    raise ImportError('Results files not found. APM did not find a solution or the server is unreachable.')
ImportError: Results files not found. APM did not find a solution or the server is unreachable.

How can I fix it? Thank you!

Answer 1

If the problem solved successfully but there is an error after the solution completed then it is likely that there was a problem retrieving the solution file from the compute server. You can eliminate the dependency on a remote server if you set the option remote to False :

m = GEKKO(remote=False)

You can see the results.csv file (solution file) in the run directory by opening the folder.

m.open_folder()