Model Error during perfrom message_ix -> tutorial ->westeros_baseline #638

[Haoyran-Wuu]

I got problems when running the module "Time to Solve Model".

FileNotFoundError Traceback (most recent call last)
Cell In[29], line 1
----> 1 scenario.solve()

File c:\Users\11456\anaconda3\envs\message_env\Lib\site-packages\message_ix\core.py:676, in Scenario.solve(self, model, solve_options, **kwargs)
656 def solve(self, model="MESSAGE", solve_options={}, **kwargs):
657 """Solve MESSAGE or MESSAGE-MACRO for the Scenario.
658
659 By default, :meth:ixmp.Scenario.solve is called with 'MESSAGE' as the
(...)
674 :class:.GAMSModel.
675 """
--> 676 super().solve(model=model, solve_options=solve_options, **kwargs)

File c:\Users\11456\anaconda3\envs\message_env\Lib\site-packages\ixmp\core\scenario.py:836, in Scenario.solve(self, model, callback, cb_kwargs, **model_options)
834 # Iterate until convergence
835 while True:
--> 836 model_obj.run(self)
838 # Store an iteration number to help the callback
839 if not hasattr(self, "iteration"):
File c:\Users\11456\anaconda3\envs\message_env\Lib\site-packages\message_ix\models.py:363, in GAMSModel.run(self, scenario)
361 optfile = Path(self.model_dir).joinpath("cplex.opt")
362 lines = ("{} = {}".format(*kv) for kv in self.cplex_opts.items())
...
1042 if "b" not in mode:
1043 encoding = io.text_encoding(encoding)
-> 1044 return io.open(self, mode, buffering, encoding, errors, newline)

FileNotFoundError: [Errno 2] No such file or directory: 'C:GAMS\for\model\files\cplex.opt'

but I do have the file named "cplex.opt" in the directory, looking looking forward ur reply（begging~）

[glatterf42]

Hi Haoyran-Wuu, thank you for this question. Did you follow our official installation instructions, in particular step 3? Because it looks like your specific GAMS solver can't be found. Please make sure the PATH environment variable contains the path to your GAMS installation.
In addition, could you please provide the output of message-ix show-versions as run on the command line? This might further clarify the issue for us.

[Haoyran-Wuu]

Thank you very much for your answer. The answer to the question above is probably YES, because I reinstalled after the first exception was reported without a solution. I will try to update the version right away!

[glatterf42]

I see. Please let me know if the new version solves the issue.

[Haoyran-Wuu]

Hi Glatter, so sorry to bother u again. I synced message-ix and ixmp to 3.7.0. Running message-ix show-versions gave the following result
(message_env) C:\Users\11456>message-ix show-versions
ixmp: 3.7.0
message_ix: 3.7.0
message_ix_models: None
message_data: None

But the weird thing is, I ran the module and it gave the same output as I've mentioned before

FileNotFoundError Traceback (most recent call last)
Cell In[37], line 1
----> 1 scenario.solve()

File ~\AppData\Roaming\Python\Python311\site-packages\message_ix\core.py:676, in Scenario.solve(self, model, solve_options, **kwargs)
656 def solve(self, model="MESSAGE", solve_options={}, **kwargs):
657 """Solve MESSAGE or MESSAGE-MACRO for the Scenario.
658
659 By default, :meth:ixmp.Scenario.solve is called with 'MESSAGE' as the
(...)
674 :class:.GAMSModel.
675 """
--> 676 super().solve(model=model, solve_options=solve_options, **kwargs)

File ~\AppData\Roaming\Python\Python311\site-packages\ixmp\core\scenario.py:836, in Scenario.solve(self, model, callback, cb_kwargs, **model_options)
834 # Iterate until convergence
835 while True:
--> 836 model_obj.run(self)
838 # Store an iteration number to help the callback
839 if not hasattr(self, "iteration"):

File ~\AppData\Roaming\Python\Python311\site-packages\message_ix\models.py:363, in GAMSModel.run(self, scenario)
361 optfile = Path(self.model_dir).joinpath("cplex.opt")
362 lines = ("{} = {}".format(*kv) for kv in self.cplex_opts.items())
...
1042 if "b" not in mode:
1043 encoding = io.text_encoding(encoding)
-> 1044 return io.open(self, mode, buffering, encoding, errors, newline)

FileNotFoundError: [Errno 2] No such file or directory: 'C:GAMS\for\model\files\cplex.opt'

So could you please tell me the reason why the operation fails again, and how to correct the solution?

[glatterf42]

I'm sorry that I don't have a lot of time to help you resolve this issue quickly. We are hosting the MESSAGEix Community Meeting this week, so a lot of time is spent on that. In the meantime, please make sure the cplex.opt file is in C:GAMS\for\model\files\ for sure. Also note that you have to select the CPLEX solver upon installing GAMS to enable its usage later on. You might need a special license to make this solver work, but your error doesn't look like a typical 'invalid license' error to me. Please also try querying your favourite search engine to see if someone else encountered and solves your issue already. Again, sorry to provide only so generic help, but we are very busy this week.

[glatterf42]

Hi again, @Haoyran-Wuu. Were you able to resolve your problem? If so, could you please tell us what you did? If not, please let me know how I can help you :)