As of HOOPS Communicator 2019, we’re now using GCC 6.3.1 (specifically, the version from devtoolset-6 6.1 on CentOS 6.9) with -std=c++11. Please note that we are not using the C++11 ABI that is used by default by GCC 5 and later, so code that calls functions in libconverter (and probably any other code that interacts with that code) needs to be compiled with the -D_GLIBCXX_USE_CXX11_ABI=0 flag. Using this flag is likely the solution to the error listed above.