After I run context (LMTX version) to my document (attached) I get this error:

tex error       > tex error on line 540 in file ./dev.tex: The file ended when scanning an argument.

I don't know how to start...
Can anyone help me?

Thanks,
Xavier

PS: I receive this error after upgrading to MKIV to LMTX. Before with MKIV I get no errors.

I suspect that LMTX is a bit more strict about parsing. You have omitted the required \par for each \head.

--
Rik