Smallest step still improving too slow

I get the message: “smallest step still improving too slow” after the iterations are complete. What does this mean, and how can I fix it?

Thank you in advance!

i suppose you are talking about the optimization using the mode_compute=4 option ( perhaps the same message comes for other optimisation routines i have not used). the message just means you have reached the mode, i dont think it is a ‘problem’ to be corrected. of course, you need to check whether the optimizer has found the right point as the mode.