2019b Warns that " Simscape Multibody First Generation libraries will be deprecated. Use Second Generation Library (sm_lib)"
It’s because Simscape Multibody no longer supports use of first-generation functions and blocks in 2020a, so it cannot find the library mblibv1 .
As a workaround, you can do any of the following
- Run files in 2019b or earlier versions
- Update the model using blocks from Simscape Multibody Second Generation Library (sm_lib).
- Use Simscape Multibody 1G Conversion Assistant tool to build Simscape Multibody 2G model that provides same behavior as 1G model.