I cannot get a PDF/A document produced with the latest MkIV beta 2020.05.18 16:46 (LMTX works without issue). Using the example from the wiki (https://wiki.contextgarden.net/PDF/A) I get the error stating:

<inserted text> ... \p_file {\backendparameter {xmpfile}}\ifempty
                                                  \p_file \else \clf_setxmpf...
\setup_backend ...end [#1]\the \everysetupbackend

l.11 ...ISO coated v2 300\letterpercent\space (ECI)]
                                                  mtx-context     | fatal error: return code: 1

Removing either of the \setupbackend instructions still results in the same error.

Same issue for PDF/X.

Is it a bug, or is it me?

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Rik