Sorry, I was thinking about %EXIT_TEXT$ but forgot the leading % when posting my response
Well, I guess you're using the Web Services stuff embedded within the newer versions of PxPlus
So far, any and all web services I have written in ProvideX were using V10 or prior versions, so were just CGI programs launched from Apache/IIS which were parsing incoming XML data and writing back XML responses to %PRINT_FN with the appropriate %CONTENT_TYPE$ and %EXIT_CODE set, and no pre-defined HTML was getting in the way if I happened to return anything else than an HTTP 200/201
So either you need to do the same, or I guess the Web Services maintenance interface needs some improvement on the PxPlus side with settings to either prevent it to spit out its predefined HTML pages in case of an HTTP 4xx ou 5xx status, or hooks to define special responses for special HTTP statuses