PulpSolverError: Pulp: Error while trying to execute, use msg=True for more details

[kaijing-zhang]

Hi Experts,

i use below scripts to load problem from JSON.
`
import pulp as lp

d, loaded_problem = lp.LpProblem.fromJson('saved_problem.json')
loaded_problem.solve()
`

it shows

At line 1594 ENDATA Problem MODEL has 341 rows, 50 columns and 704 elements Coin0008I MODEL read with 0 errors Continuous objective value is 8.3122 - 0.00 seconds Cgl0003I 0 fixed, 0 tightened bounds, 15 strengthened rows, 0 substitutions Cgl0003I 0 fixed, 0 tightened bounds, 10 strengthened rows, 0 substitutions Cgl0004I processed model has 39 rows, 21 columns (21 integer (0 of which binary)) and 126 elements Cutoff increment increased from 1e-05 to 0.9999 Cbc0012I Integer solution of 28 found by DiveCoefficient after 0 iterations and 0 nodes (0.01 seconds) Cbc0038I Full problem 39 rows 21 columns, reduced to 8 rows 11 columns Cbc0012I Integer solution of 20 found by RINS after 0 iterations and 0 nodes (0.01 seconds) terminate called after throwing an instance of 'CoinError' Exception in execute request:

then error out

could you please help me?

the saved_problem.json file is in the attachment.
saved_problem.json

[pchtsp]

This seems an issue to report to the cbc repository. https://github.com/coin-or/Cbc

Having said that, the coefficients for your constraints seem to have way more decimal digits than you need. Consider rounding all the floats on your problem to a reasonable precision (e.g., 2 digits).

That could be the cause of the error.

[kaijing-zhang]

This seems an issue to report to the cbc repository. https://github.com/coin-or/Cbc

Having said that, the coefficients for your constraints seem to have way more decimal digits than you need. Consider rounding all the floats on your problem to a reasonable precision (e.g., 2 digits).

That could be the cause of the error.

thanks for your suggestion.
but my coefficients for my constraints are all 1 or -1.
such as: a6536 + a6537 + a6538 <= 30
a6536， a6537 a6538 and are variables. they coefficients are all 1

[pchtsp]

Well if you open the json file you shared in a text editor you will see "constant" values for some constraints that have maaany decimals.

[kaijing-zhang]

Well if you open the json file you shared in a text editor you will see "constant" values for some constraints that have maaany decimals.

Thanks a lot. i will try.
how to send the case to CBC? same as my description here ans send the json to them?