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?

-- 
Rik