Error Message "Singular Matrix in LUDCMP -STOP"

I am solving a multi-dimensional function using fsolve. I am trying to solve it using GA tool but then reverted and wanted to run the function using fsolve once again. Although I removed the GA solver, an error message "Singular Matrix in LUDCMP -STOP" keeps popping up in the command line. Is there a way to stop this? I have closed all the windows and even tried to run another code and the error message keeps coming. It seems the GA tool changed a setting or so. I appreciate your inputs.

I am using MATLAB R2020b, if that helps.

[Walter Roberson]

That is a message from a function LUDCMP which is LU Decomposition. However, at the moment I do not see any evidence that it is used by MATLAB.

Try

restoredefaultpath; rehash toolboxcache

and see if the problem goes away. If it does then you have something added to your MATLAB path that is interfering.

[Omar Khalifa]

I tried the rehash. But no luck, it still shows the same message. The error message appears sporadically, as if something on the back is trying to run along with the code, yet the code itself did not converge as it did before.

[Omar Khalifa]

I tried to run a code in a different path and it did not show the error message.

[Omar Khalifa]

I copied and pasted the code in another directory and it did not show the error message anymore. I do not know what was wrong!

[Walter Roberson]

Something in the original directory was interfering