Frank Küster wrote:
Hm, can you give me a short hint
- what tells you that it's a macro error, and
That snippet was the actual error context so you have to read it upside down, and there is a bit of information missing. The general overview is: \makebm expands into something containing \bm that expands into something containing \bm@command that expands into something containing \bm@gr@@p that expands into something containing \bm@mchoice that expands into something containing \makebm ... (full circle)
- where the error probably is?
It seems \makebm is an internal macro of the bm package, and the document-level definition of \makebm to redefines that macro. Perhaps this is the result of a recent update of the bm package. At least that would explain why the documentation may have been run with errors in the past. There is a simple solution: use a different macro name for the in-document definition. Best wishes, Taco