A further observationthat makes things seem far worse: the error is dependent on the content!
The document in question has several chapters, each in a separate file. Dependent on the combination of files included, the error does or does not show up. Sofar I cannot find a pattern linked to the error. Making a minimal example proved impossible, alas.

Hans van der meer

> On 27 Dec 2015, at 13:19, dr. Hans van der Meer <havdmeer@ziggo.nl> wrote:
> 
> 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?
> 
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