begin{tabulary}{linewidth}{|L|L|L|}
hline
textsf{relax
Nummer
} & textsf{relax
Name
} & textsf{relax
Bemerkungen
}\
hline
0
 &
Allgemeines
 &
Enthält Meta-Informationen zum Dossier
\
[...]
hlineend{tabulary}

RequirePackage{tabu}

definecolor{tablehead}{rgb}{0.7294117647058823, 0.6823529411764706, 0.6235294117647059}

renewenvironment{tabulary}[2]{bgroupbegin{tabu} to textwidth{#2}
    rowcolor{tablehead}
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{end{tabu}egroup}

! Missing # inserted in alignment preamble.
<to be read again>
                   &
l.294 hlineend{tabulary}

? x