Happily there proved to be a remedy: place everything inside = an \hbox and the error goes away. Without problematic whitespace or = other nasty side effects, it seems. But, although the panic is = over now :-), I am still curious to know why it worked before and raises = an error now.

as= for the definition of \placexlocation, it comes from:

\def\setupplacex{\getparameters[placex]}

\setupplacex[% default = parameters

...

= location=3Dcenter,%

...

and = I checked that it had the value: center.

But if you are interested, I can send = you the module code.

dr. Hans van der Meer

On 7 Jun 2020, at 12:20, Wolfgang Schuster <wolfgang.schuster.lists@gmail.com> wrote:

Hans = van der Meer schrieb am 07.06.2020 um 12:07:
A problem has arisen up since previous = versions, where code without a problem now raises an error.
This is the afflicted code:
% Assign values to = \locationbox.
\doif{top}{\placexlocation}%
{\def\startlocationbox{\vtop\bgroup\vss}}%
\doif{center}{\placexlocation}%
{\def\startlocationbox{\vcenter\bgroup}}%
\doif{bottom}{\placexlocation}%
{\def\startlocationbox{\vbox\bgroup}}%
And it = is used here:
\setbox\placexbox=3D\startlocationbox
\ignorespaces
Previously this worked without a = hitch, now the error is:
tex error = > tex error on line 9 in file ./familie-events.tex: ! A <box> = was supposed to be here
<to be read again>
\vcenter
\startlocationbox ->\vcenter
= \bgroup
\dostartcontentplacexinline ...ables \par \setbox \placexbox = =3D\startlocationbox
=             &n= bsp;           &nbs= p;            =             &n= bsp;           &nbs= p;            = \ignorespaces
<to be read = again> \syst_helpers_single_empty_one_nop
= = \xmlflush
\21>:xmlplc:placexcontent ...le=3D\xmlatt = {#1}{alttitle}]}\startcontent \xmlflush
=             &n= bsp;           &nbs= p;            =             &n= bsp;           &nbs= p;            = {#1}\stopcontent
l.9 }
I= can try to make a minimal example, but not without the afflicted module = of some 800 lines. So perhaps the problem will be located by the experts = at first sight. It is of course the \vcenter playing havoc, because = replacing it by \vtop or \vbox makes the error disappear.
Thanks for looking into it, because my work more or less = depends on this code working in good order.
How so you define \placexlocation?

Wolfgang
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