Simulink Sfunction Error - not a valid Win32 application

Since I have installed a Windows update I am getting the following error: Error calling generated SFunction, XXXX_sfun. Invalid MEX-file 'H:\MATLAB\XXXX_sfun.mexw64': H:\MATLAB\XXXX_CTD_sfun.mexw64 is not a valid Win32 application.

If I remove one of the SFunctions from the model I no longer get the error. If I put that SFunction back into the model and remove a different SFunction from the model I no longer get the error.

There are no global variables.

The model worked before the Windows update. I have changed some formulas in the functions but nothing too significant. Running the Matlab code associated with the SFunctions by itself works fine, so I don't think it is a coding bug.

Not sure where to go from here.

Answer 1

[Madhura Suresh]

It is possible that the bitness of the S function and MATLAB or some of the modules have a bitness mismatch. Is it possible that the S function module is 32 bit, and everything else might be 64 bit? You can check the bitness of MATLAB by using

>> mexext

[Chris]

mexext gives me mexw64 as I would expect. I don't understand why the S function module would be 32 bit? The module is compiled in a 64 bit version of Simulink running on Windows 7.

Answer 2

[Kaustubha Govind]

My guess is that your update either wiped out your system PATH environment variable or uninstalled your Visual C++ redistributables (these are runtime libraries that binaries compiled with Visual Studio depend on). I would recommend trying to reinstall the Visual C++ redistributables corresponding to the version of Visual Studio that you used to compiled the MEX-files. You should be able to find them from Microsoft's Download Center.

If that doesn't help, you can use Dependency Walker to figure out if you are missing any other dependencies.

[Chris]

Re-installing the Visual C++ redistributables didn't fix the problem unfortunately. I have to say the procedure for uninstalling and re-installing the C++ compiler is very painful. Not all entries in the registry seem to removed during the uninstall process. So manual intervention is required.

Dependency Walker indicated a problem with 2 files, IESHIMS and MSVCR80.

[Kaustubha Govind]

Chris: Do both DLLs exist on your machine and on the System PATH variable?

[Chris]

Both DLLs exist on the machine. In regards to the System PATH variable, I assume you are referring to the MATLAB Path. If this is the case then no they are not in any of these Paths. They are primarily located in "C:\Windows\winsxs\" path. But I would assume the location would be more related to the compiler, rather than Matlab.

[Abdulla Hammad]

Dependency Walker was a very useful tip. I discovered I am using a Win32 bit version of the DLL instead of 64bit.

Thank you Kaustubha Govind, Abdulla