Hi Marcin, On 13/10/2021 13.18, Marcin Puchlik wrote: > /1: ImportError: /home/ubuntu/gr-howto/build/swig/_howto_swig.so: undefined > symbol: _ZN2gr5howto10square2_ff4makeEv/
You can convert/demangle the symbol using the c++filt command c++filt _ZN2gr5howto10square2_ff4makeEv gr::howto::square2_ff::make() Make sure that you have implemented square2_ff::make() function and then check the .so file for undefined symbols. cd /home/ubuntu/gr-howto/build/ ldd -r ./lib/lib*.so objdump -TC ./lib/lib*.so | grep make You can also attempt a clean rebuild (delete the build directory) or in case you have installed a previous version of your OOT module then try uninstalling it - run `make uninstall` Regards, Vasil
