Dear list, I have the following sample: \setupheadertexts[{\getmarking[chapter]}] \starttext \chapter{Chapter} \stoptext It compiles perfectly fine with MkIV from 2021.10.08 20:18, but its LMTX version triggers the following error message: Undefined control sequence \??markingfilter Previous LMTX version compiled just fine. I think it might be a bug. Many thanks for your help, Pablo -- http://www.ousia.tk