How to resolve errors with syms/sym function?

I am facing some error while I am using syms/sym function:

Invalid MEX file, specific module cannot be found

How to resolve the above error?

Answer 1

[MathWorks Support Team]

These types of issues happen due to path issues and also when the cache is not up to date. The following steps will help resolve this issue. 

Before modifying the search path, it is important to take a backup of your 'pathdef.m' file, which can be located by using the following command. Ensure that the copy is placed in a folder outside of the MATLAB path.

>> which -all pathdef

After taking the backup, please execute the following commands in the MATLAB Command Window to restore the default MATLAB search path and rehash the toolbox cache:

>> restoredefaultpath
>> rehash toolboxcache
>> sl_refresh_customizations 

After this step, please use MATLAB/ Simulink to see if the issue occurs again. If the issue is resolved, then you may want to save the new MATLAB search path by executing the following command:

>> savepath

NOTE: This will remove any custom paths you may have created.

The following MATLAB Answers post is an additional resource on how to back them up:

https://in.mathworks.com/matlabcentral/answers/166871-how-will-running-the-restoredefaultpath-and-savepath-commands-affect-my-custom-paths-and-how-do