Mclmcrrt9-9.dll -

Because this DLL is central to MCR functionality, errors are frustrating but usually consistent. Below are the most common error messages you may encounter:

Sometimes the DLL loads, but an internal MCR error occurs, such as: mclmcrrt9-9.dll

Since mclmcrrt9-9.dll comes specifically with MCR 9.9 (R2019b), you must install that exact version. A newer MCR (e.g., v9.10 for R2020a) will contain mclmcrrt9-9.dll ; it will have mclmcrrt9-10.dll . Because this DLL is central to MCR functionality,

If it does not exist, click and add the path to your runtime\win64 folder. but an internal MCR error occurs