Forum Discussion
getCallbackSolution failing and yielding error 422 inside a chgbranchobject callback?
Hi sll,I'm using the Python API of the Xpress Optimizer to try and implement through the addcbchgbranchobject callback a custom branching choice during a MIP search.According to the reference manual,...
According to the documentation getCallbackSolution() from within a chgbranchobject callback should indeed return the current relaxation.
I cannot reproduce your problem, though. I tried several problems with Xpress 45.1.2 and called getCallbackSolution() for each and every invocation of the callback. I did not observe any problem.
What version of Xpress are you using? What object are you calling getCallbackSolution() on? You must call it on the problem object that is passed as first argument into the callback, not on the problem object on which you called optimize(). Can you share your code or provide a short example that reproduces the problem?