Error 126 MDL Loader: Unable to load library (DLL or MDL shared library) mcmtb

Error 126.  
MDL Loader: Unable to load library (DLL or MDL shared library) mcmtb 

Product(s) and Version(s):  

MicroStation integrated with ProjectWise Explorer 

Problem:   

When trying to open a design file in an integrated ProjectWise Explorer environment using MicroStation, the following error message is displayed:, 

OS could not load C:\PROGRA~1\Bentley\PROJEC~1\bin\v1000\mcmtb.dll, error 126. 

MDL Loader: Unable to load library (DLL or MDL shared library) mcmtb 

The design file opens, however, attribute exchange does not work. The relevant key-ins like titleblock updatedms are not recognized. 

Solution: 

The following path must be added to the MicroStation configuration variable of MS_LIBRARY_PATH, 

C:\Program Files\Bentley\ProjectWise\bin\v1000 

The above directory should be available in the variable of MS_LIBRARY_PATH, by default. However, if the directory is not enlisted, it will cause the above-described issue. 

1. Open any file in MicroStation. Select File> Settings> Configuration> Configuration Variables. 

1. In the ‘Configuration Variables’ dialog that follows, search for the variable,  
   MS_LIBRARY_PATH 

1. Click on the Edit button. Change the Edit mode to ‘Append’. In the ‘New Value’ field, enter the following directory, 
   C:\Program Files\Bentley\ProjectWise\bin\v1000 
   Click on OK. This will add the variable to the User Preferences file, which is located in the following directory, 

C:\Users\<username>\AppData\Local\Bentley\MicroStation\10.0.0\prefs 

Restart MicroStation.