coin-or / coin-or/pulp

different behavior with different versions of highs solver

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HiGHs
Dominant language
Python
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Description

Solving a MIP, using PuLP 3.30 and Python 3.13 the highs solver runs as expected when using highs version 1.11 but fails when using 1.12.

--------------------

#### What did you do?
MIP modelled in PuLP în Variable prob

`from pulp import HiGHS_CMD`
`...`
`# problem modelled in variable prob`
`...`
`status = prob.solve(HiGHS_CMD(path="highs_v1.12.exe"))`

#### What did you expect to see?
a running programm finding some status

#### What did you see instead?
FileNotFoundError: [Errno 2] No such file or directory: '...\\fbc02af1ef7e4be39614a63d468dadb8-pulp.HiGHS_log'

Useful extra information
-------------------------
doing the same with highs 1.11 everything works as expected

`from pulp import HiGHS_CMD`
`...`
`# problem modelled in variable prob`
`...`
`status = prob.solve(HiGHS_CMD(path="highs_v1.11.exe"))`

both versions of highs.exe are the precompiled binaries

#### What operating system are you using?
- [X] Windows: ( _version: 11 )

#### I'm using python version:
- [x] 3.13

#### I installed PuLP via:
- [X] pypi (python -m pip install pulp) , version 3.3.0

#### Did you also
- [ ] Tried out the latest github version: https://github.com/coin-or/pulp
- [X] Searched for an existing similar issue: https://github.com/coin-or/pulp/issues?utf8=%E2%9C%93&q=is%3Aissue%20
found one but I use the precompiled binaries in the working and not working case, so self compiling didnt cause the issue

Contributor guide

Open the contributing guide

Research direction

Start at the PuLP HiGHS_CMD entry point and reproduce the reported Windows 11 failure with Python 3.13, PuLP 3.3.0, and the two precompiled HiGHS versions. Compare the solver invocation and log-file handling for 1.11 and 1.12; done means the 1.12 binary completes the MIP solve and returns a status without FileNotFoundError.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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