[NTG-context] suddenly run error

A document that runs fine under ConTeXt ver: 2015.10.09 21:28 MKIV beta fmt: 2015.10.11 int: english/english suddenly doesn't under ConTeXt ver: 2015.12.22 10:50 MKIV beta fmt: 2015.12.27 int: english/english mtx-context | fatal error: no return code, message: luatex: execution interrupted Loaded this beta today. The previous beta runs ok, the new beta gives the error. The pdf produced in the latter seems at fault. Anyone knows how this error can occur?