Why is the "codegen" command failing with the error message “ninja: build stopped”?

I am attempting to generate a MEX file from MATLAB code using MATLAB Coder. 

Every time I execute the "codegen" command to build a MEX file, I get a long list of OBJ files that failed and an error message from ninja that the build stopped. For example, see the following error message snippet:

FAILED: build/win64/c_mexapi_version.obj
 
cl /c /Zp8 /GR /W3 /EHs /nologo /MD /D_CRT_SECURE_NO_DEPRECATE /D_SCL_SECURE_NO_DEPRECATE /D_SECURE_SCL=0 /DMATLAB_MEX_FILE /DMATLAB_MEX_FILE /O2 /Oy- /DNDEBUG /fp:strict /I "." /I "D:\matlabTestLib" /I ".\interface" /I "C:\Program Files\MATLAB\R2020b\extern\include" /I "." -DMODEL=MTL_mex "C:\Program Files\MATLAB\R2020b\extern\version\c_mexapi_version.c" /Fobuild\win64\c_mexapi_version.obj
 
CreateProcess failed: The system cannot find the file specified.
ninja: build stopped: subcommand failed.
 
 
------------------------------------------------------------------------
??? Build error: C compiler produced errors. See the Build Log for further details.
More information
Code generation failed: View Error Report
Error using codegen

Why do I get this error message, and how can I generate code without this error?

Answer 1

[MathWorks Support Team]

To resolve the above error, run the following command:

mex -setup

 and choose a new value for the desired compiler. Then, repeat this for

mex -setup C++

If the above steps do not work, it may mean that the cause of the issue is that the compiler was updated without executing "mex -setup". A possible workaround for this is to clear the existing XML files that specify which compiler the "mex" process will use, using the following steps: 

1.  At the MATLAB command line, execute:

>>cd(prefdir)

2. Delete the files "mex_C_win64.xml" and "mex_C++_win64.xml" in the MATLAB current directory.

3. Execute the "mex -setup" commands at the MATLAB command line again.