I am having an issue with Solver since I upgraded from Excel 2011 to Excel 2016 for Macbooks.
I set up a problem that I want to use solver on, and I was able to successfully add Solver through the Tools menu.
I open solver (screenshot below):

Usually I am able to select cells after I open Solver but not since I installed Excel 2016. The reason you see the cells selected in the solver window in the above screenshot is because that was set up in Excel 2011. Then I thought maybe there is a compatibility
issue with old Excel workbooks. So I set up a new problem in Excel 2016 and tried to use Solver, again same issue can't select cells, so I typed them up in the solver window and clicked on "Solve", and in both cases I get the following error message:

Is anybody facing a similar issue?
I really need Solver to work, and at the moment it seems the only viable option is to downgrade to Office 2011...