Thanks, Massimo! I thought that (redundantly)
routes_onerror = [ (r'sandbox_luis/*', r'/sandbox_luis/static/fail.html') (r'*/*', r'/sandbox_luis/static/fail.html') ] would catch all errors, but https://domain.net/sandbox_luis/default/contact_person? results in Bad Request and https://domain.net/sandbox_luis/default/contact_pers results in invalid function (default/contact_pers) How do I detect and re-route these kinds of errors? Thanks, Luis.