I have only seen this problem with the latest version of Linux Mint. I do not understand what has gone wrong, but found that applying the following before calling the install script or umk, resolved the problem for me.
I also added them into the include and library path of TheIDE to enable the projects to build.
# Require these include paths for Linux Mint 21.1
export CPLUS_INCLUDE_PATH=/usr/include/c++/11:/usr/include/x86_64-l inux-gnu/c++/11
export LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/11