mclmcrrt7x.dll is a run-time library needed to run MATLAB Compiler generated applications on deployment machines that do not have MATLAB and MATLAB Compiler installed. This library is installed during the course of the MATLAB Compiler Runtime (MCR) installation.
This error typically results from one of two situations:
1. The correct version of MATLAB Compiler Runtime (MCR) is not installed.
Applications generated with MATLAB Compiler depend on the version of the run-time library specific to the version of the MATLAB Compiler that generated the application.
You can find the install program for the MCR in the following sub directory of the MATLAB installation which created the program.
$MATLABROOT\toolbox\compiler\deploy\win32\mcrInstaller.exe
or
$MATLABROOT\toolbox\compiler\deploy\win64\mcrInstaller.exe
(where $MATLABROOT is the MATLAB root directory on your machine, as returned by typing:
matlabroot
at the MATLAB command prompt.)
Instructions for installing the MCR are located in the documentation:
Deploying to End Users :: Deployment Process (MATLAB Compiler)
Running MCRInstaller.exe on the deployment machine will install the MCR, including the mclmcrrt7x.dll:
$MCRROOT\v$VER\runtime\win32\mclmcrrt$VER.dll
($MCRROOT is the MATLAB Compiler Runtime root directory that was chosen during the MATLAB Component Runtime installation process. This typically defaults to something like C:\Program Files\MATLAB\MATLAB Compiler Runtime. $VER is the MCR version number without the periods.)
The “missing mclmcrrt7x.dll” error message will result if you have not installed the version of the MCR that corresponds to the version of MATLAB Compiler the application was compiled with. For example, if you have installed the MCR for MATLAB Compiler 4.9 (R2008b), version 7.9 of the mclmccrt DLL will be installed in, for example:
C:\Program Files\MATLAB\MATLAB Compiler Runtime\v79\runtime\win32\mclmcrrt79.dll.
For releases prior to R2008a the runtime libraries will be located in a slightly different directory tree:
C:\Program Files\MATLAB\MATLAB Component Runtime\
Now, if an application generated using MATLAB Compiler 4.6 (R2007a) is executed on this computer without installing that version of the MCR, the "missing mclmcrrt76.dll" error would result.
2. A second option is that the system's PATH environment variable was not set correctly.
During the course of the MATLAB Compiler Runtime installation, the following directory should have been added to your system path:
$MCRROOT\v$VER\runtime\win32
To work around this issue, manually update the PATH environment variable on your deployment machine to include the following directory:
$MCRROOT\v$VER\runtime\win32
For instructions on modifying your system PATH environment variable, refer to the solution referenced below.
Also note that since these DLLs have different names for each version of the MCR, multiple versions of the MCR can be installed on the same machine.
