X_PIPELINE_FINALIZE_FAILED
Means
a finalize stage threw instead of finishing the response
Typical cause
the response cannot take the headers the pipeline puts on it — a Response.redirect(), or a frozen or proxied Response a handler returned. handle() answers this 500 rather than rejecting, and the cause names the stage
Fix
return a Response built here — jsonResponse(), textResponse(), html() or redirect() from @ultimat3/http