Tcl 9 is incompatible with 8. See below links for major incompatibilities and more info. https://www.tcl-lang.org/software/tcltk/9.0.html https://core.tcl-lang.org/tcl/wiki?name=Migrating+scripts+to+Tcl+9 https://wiki.tcl-lang.org/page/Porting+extensions+to+Tcl+9 https://github.com/apnadkarni/tcl9-migrate