This article is a "quick overview" of possible causes for the error message:
Invalid cell value at: <cell address>
This error message can occur during diagnosis or "Solve time", and looks like similar to this in the Solver Options and Model window pane Output tab:
If you encounter this error, please check the cells indicated for the following:
- Any #<Error> values in those cells (I.E. #NUM, #VALUE, #DIV/0, etc). These are Excel based errors and typically mean a value can not be "evaluated" properly by Excel's own calculations. Wrapping functions in cells containing these errors in an IFERROR function (more information here) can help get past them, though you will typically want to find and resolve the root of the error to ensure the optimization performs properly.
-- Note: Use of IFERROR can be helpful with global optimizations (I.E. using GRG with Multi-start or the Evolutionary engine) that may test points where a denominator will be 0 (causing a #DIV/0 error).
- Any "merged" cells involving the cell addresses listed. This includes cells containing variables, constraints, or the objective (any cell used in the Optimization process). For example, if you set cell A1 to be a variable in an optimization model, merge cells A1 and A2 within Excel, and try to execute a solve you will receive the above error message at "Solve time". More information on "merging and unmerging" cells can be found here.
If the error persists and you can not find the root of the cause based on the information above, please let us know via email to firstname.lastname@example.org.