@royf, Without more information, we can only speculate what kind of crash you are seeing.  But based on past experience, it is almost certainly a crash in Tk itself and, if so, you need to work with your supplier of Tk, presumably the conda project, to get a working version of Tk 8.6.x. Our most recent experience with building Tk on macOS for the python.org installers found that using the released Tk 8.6.8 source tarball (ftp://ftp.tcl.tk/pub/tcl//tcl8_6/tk8.6.8-src.tar.gz) was the least problematic at the moment.