Wrong folder for PULP_CBC_CMD on OSX arm64

[ianlokh]

Details for the issue

What did you do?

Run pulp with PULP_CBC_CMD

What did you expect to see?

Solver executing successfully

What did you see instead?

I got the following error:
"Traceback (most recent call last): File "/Users/ianlo/PycharmProjects/optimizer/main.py", line 100, in <module> prob.solve(pulp.PULP_CBC_CMD(msg=True, timeLimit=300, threads=6, gapRel=0.05)) File "/opt/homebrew/Caskroom/miniforge/base/envs/torch_py311/lib/python3.11/site-packages/pulp/pulp.py", line 1996, in solve status = solver.actualSolve(self, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/opt/homebrew/Caskroom/miniforge/base/envs/torch_py311/lib/python3.11/site-packages/pulp/apis/coin_api.py", line 354, in actualSolve raise PulpSolverError( pulp.apis.core.PulpSolverError: PULP_CBC_CMD: Not Available (check permissions on /opt/homebrew/Caskroom/miniforge/base/envs/torch_py311/lib/python3.11/site-packages/pulp/solverdir/cbc/osx/arm64/cbc) "

Useful extra information

The info below often helps, please fill it out if you're able to. :)

What operating system are you using?

• Windows: ( version: ___ )
• Linux: ( distro: ___ )
• Mac OS: ( _version:15.3.1 (24D70) )
• Other: ___

I'm using python version:

• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• Other: ___

I installed PuLP via:

• pypi (python -m pip install pulp)
• github (python -m pip install -U git+https://github.com/coin-or/pulp)
• Other: pip install -U pulp (conda?)

Did you also

• Tried out the latest github version: https://github.com/coin-or/pulp
• Searched for an existing similar issue: https://github.com/coin-or/pulp/issues?utf8=%E2%9C%93&q=is%3Aissue%20

[ianlokh]

Hi

I realised that this was a directory name issue. On my Mac the install was:
"/opt/homebrew/Caskroom/miniforge/base/envs/torch_py311/lib/python3.11/site-packages/pulp/solverdir/cbc/osx/64/cbc"

However the code was trying to call
"/opt/homebrew/Caskroom/miniforge/base/envs/torch_py311/lib/python3.11/site-packages/pulp/solverdir/cbc/osx/arm64/cbc"

So when I renamed the directory, I could run the solver.

Looks like an installation / setup issue?

[ngast]

Hi,

I am having the same issue here: Macos 15.3.1 with python 3.13 and pulp freshly installed with pip: pulp does not find the solver but if I rename "...solverdir/cbc/osx/64/cbc" into "...solverdir/cbc/osx/arm64/cbc" then the code works.

[pchtsp]

As I understand this is exactly the symmetric problem. Maybe we're detecting the architecture wrong.
Can you check the file:

pulp/pulp/apis/core.py

Lines 152 to 184 in 7c8aa93

	PULPCFGFILE = "pulp.cfg"
	is_64bits = sys.maxsize > 2**32
	if is_64bits:
	arch = "64"
	if platform.machine().lower() in ["aarch64", "arm64"]:
	arch = "arm64"
	else:
	arch = "32"
	operating_system = None
	if sys.platform in ["win32", "cli"]:
	operating_system = "win"
	PULPCFGFILE += ".win"
	elif sys.platform in ["darwin"]:
	operating_system = "osx"
	PULPCFGFILE += ".osx"
	else:
	operating_system = "linux"
	PULPCFGFILE += ".linux"
	DIRNAME = os.path.dirname(__file__)
	config_filename = os.path.normpath(os.path.join(DIRNAME, "..", PULPCFGFILE))
	(
	cplex_dll_path,
	ilm_cplex_license,
	ilm_cplex_license_signature,
	coinMP_path,
	gurobi_path,
	cbc_path,
	glpk_path,
	pulp_cbc_path,
	scip_path,
	fscip_path,
	) = initialize(config_filename, operating_system, arch)

In particular, this is how we find out the path to the binary:

impor sys
import platform

is_64bits = sys.maxsize > 2**32
if is_64bits:
    arch = "64"
    if platform.machine().lower() in ["aarch64", "arm64"]:
        arch = "arm64"
else:
    arch = "32"

In any case, you can always run the COIN_CMD and passing the path to the binary via the path argument.
See here:
https://coin-or.github.io/pulp/technical/solvers.html#pulp.apis.COIN_CMD

[ngast]

I think that it is the same problem: pulp looks for the cbc in the directory "arm64" but it was installed in the directory "64".

Note that on my machine, your code sets the variable arch to 'arm64' (macbook pro M4).

[davidggphy]

Having the same problem here.
Apple M3 Pro
macOS 15.3.1 (24D70)
Python 3.11
Pulp 3.0.2

This is, running a "pip install pulp" installs CBC at
~/miniconda3/envs/conda_env/lib/python3.11/site-packages/pulp/solverdir/cbc/osx/64

But the code @pchtsp posted returns arch="arm64", making pulp look for CBC at

import pulp
pulp.pulp_cbc_path

~/miniconda3/envs/conda_env/lib/python3.11/site-packages/pulp/solverdir/cbc/osx/arm64/cbc which is unexistent

Indicating the correct path when setting the solver:

# Resolver el problema
solver = pulp.PULP_CBC_CMD(
    path=pulp.pulp_cbc_path.replace("arm64", "64"),
    msg=True, 
)
model.solve(solver)

Does not solve the problem (it still looks for the default path with arm64):

PulpSolverError: PULP_CBC_CMD: Not Available (check permissions on ~/miniconda3/envs/conda_env/lib/python3.11/site-packages/pulp/solverdir/cbc/osx/arm64/cbc)

[sebastian-correa]

Having the same problem with PuLP 3.0.2 (but not with 2.9.0) in a Mac M1 (15.1 (24B83)) with Python 3.10 (Python 3.10.15 (main, Jan 22 2025, 10:10:59) [Clang 16.0.0 (clang-1600.0.26.4)]).

❯ eza .venv/lib/python3.10/site-packages/pulp/solverdir/cbc/osx
64

So no arm64 directory there.