Tools > Options > Languages > Application Languages > C/C++ > Compiler Properties
I've got several custom compilers defined.
For each I have a header file, like:
C:\Users\josepo03\Documents\SlickEdit\20.0.3\tagfiles\usercpp_blat.h
So, in Slick 21, even though it copied those headers to Slickedit\21.0.0\tagfiles, it didn't update these paths.
These header paths still point to the old V20 slick configuration.
The tagfile paths did get updated.