Hi Hans, I just updated to the latest version 2020.05.09 08:55 but when trying your examples with \mathopenup and friends noticed that ConTeXt is stuck with resolvers > lua > loading file '/context-osx-64/tex/texmf-context/tex/context/base/mkiv/math-spa.lua' succeeded or with context report > file: cont-en-status.html and other such messages. Actually even with a simple example like \starttext Test \stoptext one cannot run the latest version at least on MacOS X (I did remove the texmf cache). When in a Terminal window I issue the commands context --make -all I see that there is an error message like: tex error > tex error on line 2981 in file math-ini.mkxl: ! Undefined control sequence l.2981 \normalsupmarkmode \plusone % 2 also disable ^[^+] in text mode <empty file> The control sequence at the end of the top line of your error message was never \def'ed. You can just continue as I'll forget about whatever was undefined. Best regards: OK