GA cannot satisfy box constraint

[nextx, mEI, exitflag] = ga(opt.crit, 4, [], [], [], [], [0.6 0.6 0.6 0.6], [6 6 6 6]);

I was running GA with only box constraint on the design variables. But I got the following error message:

Optimization terminated: average change in the fitness value less than options.FunctionTolerance.
Linear constraints are not satisfied within constraint tolerance.

I found on the page: https://www.mathworks.com/help/gads/constrained-minimization-using-ga.html

For problems without integer constraints, the genetic algorithm solver handles linear constraints and bounds differently from nonlinear constraints. All the linear constraints and bounds are satisfied throughout the optimization.

Apparently, the bounds are not satisfied.

[Arvind Narayanan]

Did you try reducing the constraint tolerance and re-run the optimization?