Gurobi sets all decision variables and objective to 0

Awaiting user input

Wieger Prinsze

June 14, 2023 10:00 Edited

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Hi, 

I am working on a routing problem (MILP), programmed using Pyomo and solved in Gurobi. When I look at the solver output, all variables are read well and the range matrix seems okay. The model is feasible and the termination conditions are ok and optimal. What could be the reason for Gurobi to solve all decision variables to zero, including the objective function? I have looked into my code thoroughly, so I'm quite sure there are no typos/modelling errors. 

Many thanks for your help!

Related to

• Wrong Result
• Pyomo

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:42

  This post is more than two years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum, or try Gurobot, our chatbot interface offering instant, expert-level support.
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  Jaromił Najman

  • Gurobi Staff

  June 15, 2023 07:57

  Hi Wieger,

  Do you mean that the solution point \(\texttt{\mathbf{x}^* = 0}\) is not correct? Did you try fixing all variables to \(0\) by hand to see why it makes sense for your model? What are the solution and objective values you expect to be optimal for your model? If you know of a feasible solution, you could try passing it as a MIP Start.

  Best regards, 
  Jaromił

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