Comments on: Help

By: Rebecca

Rebecca — Wed, 25 Feb 2026 07:59:01 +0000

In reply to Andrew Mason (Team OpenSolver).

Thanks, I’ll give that a try but it works up until the point I try to add those constraints.

By: Andrew Mason (Team OpenSolver)

Andrew Mason (Team OpenSolver) — Tue, 17 Feb 2026 20:37:10 +0000

In reply to Rebecca.

You need to write such constraints carefully, making sure they are linear (eg, not multiplying decision cells together). However, that error message suggests you are doing something else that’s not quite correct. You may wish to get a working model (without all the constraints you want), then use the “View Last Model File” to get a .lp file you can give to ChatGPT, and ask it to add the extra constraints so you can see their format. Hope this helps, Andrew

By: Rebecca

Rebecca — Tue, 17 Feb 2026 11:28:47 +0000

I am using OpenSolver 2.9.3 and have a query about interactions between decision variables. I have 100 objects that I am assigning to 10 groups. Each object needs to go into 2 groups and each group will have 20 objects. I have set up the variables cells and added a column that sums across the 10 groups. I’ve set a constraint for the sum across columns to equal 2. This solves without any issues. However, I also want to control the overlap between groups so that each group has a maximum number of objects in common with another group. I’ve tried various different ways of adding constraints to do this but each time I get an error stating that instance n does not depend on the decision variables. I don’t think this is the case because the functions that I am using are based on the columns with the group assignment (i.e. the columns specified as the variable cells).
Is this expected? Should it be possible to add constraints based on a combination of the decisions/variable cells?

By: Andrew Mason (Team OpenSolver)

Andrew Mason (Team OpenSolver) — Sat, 29 Nov 2025 22:52:07 +0000

In reply to Steve Nied.

Thanks for the update that rebooting fixed he problem. I am not sure why, but rebooting is often mysterious! Andrew

By: Steve Nied

Steve Nied — Sat, 29 Nov 2025 22:38:07 +0000

Never mind, please! I rebooted and the buttons are now working

By: Steve Nied

Steve Nied — Sat, 29 Nov 2025 22:27:50 +0000

Hi, I have installed OpenSolver in Office 365, and it shows up in the Data tab. I have enabled VBA Macros in Macro Settings and made the file location trusted. However, the buttons do not do anything when clicked. I read the FAQ about clicking on “About OpenSolver …” but again this does nothing. Any ideas on other settings I need to change?

By: Andrew Mason (Team OpenSolver)

Andrew Mason (Team OpenSolver) — Fri, 28 Nov 2025 06:25:32 +0000

In reply to Sara.

I would start by checking the RefEdit status; see our Help Page for info on this.

By: Sara

Sara — Wed, 26 Nov 2025 14:04:07 +0000

Hi
When I try to add in the opensolver I get the class not registered Looking for object with CLSID error. I have excel 2016.
would appreciate any help troubleshooting this.

By: Paul John

Paul John — Mon, 17 Nov 2025 19:33:57 +0000

Is there a simple coding tweak to enable Gurobi 13 to work with Opensolver and overcome the error

“No Gurobi installation was detected. The following file was not found: “C:\gurobi1203\win64\python27\bin\python.exe”

A few years ago I recall it was possible to edit one of the modules in the xlam file to get it to work with the then new Gurobi version.

By: Andrew Mason (Team OpenSolver)

Andrew Mason (Team OpenSolver) — Thu, 06 Nov 2025 00:19:45 +0000

In reply to Daryl Greene.

Thanks for your detailed instructions, and your innovative coding. However, once a solver like CBC starts solving, OpenSolver has no way to change any of the Branch and Bound settings, so calling SetTolerance at this time will not work. Sorry to be the bearer of bad news! Andrew