Not in outer par mode

For example:

*\mbox{\marginpar{foo}}

! LaTeX Error: Not in outer par mode.

The error comes when you try to build something movable inside a box. Movable things, in this context, are floating environments (figure and table, for example), and \marginpars. LaTeX simply doesn’t have the mechanisms for floating out of boxes. In fact, floats and \marginpars themselves are built out of boxes, so that they can’t be nested.

If your error arises from \marginpar, you simply have to think of an alternative way of placing the command; there is no slick solution.

If a floating environment is the culprit, it may be possible to use the H placement option, provided (for example) by the float package:

\parbox{25cm}{%
  \begin{figure}[H]
  ...
  \caption{Apparently floating...}
  \end{figure}%
}

This example makes little sense as it stands; however, it is conceivable that sane uses could be found (for example, using a package such as algorithm2e to place two algorithms side-by-side).

Annother common occurrence is when the user wants a figure somewhere inside a table:

\begin{tabular}{|l|}
  \hline
  \begin{figure}
  \includegraphics{foo}
  \end{figure}
  \hline
\end{tabular}

a construction that was supposed to put a frame around the diagram, but doesn’t work, any more than:

\framebox{\begin{figure}
  \includegraphics{foo}
  \end{figure}%
}

The problem is, that the tabular environment, and the \framebox command restrain the figure environment from its natural métier, which is to float around the document.

The solution is simply not to use the figure environment here:

\begin{tabular}{|l|}
  \hline
  \includegraphics{foo}
  \hline
\end{tabular}

What was the float for? — as written in the first two examples, it serves no useful purpose; but perhaps you actually wanted a diagram and its caption framed, in a float.

It’s simple to achieve this — just reverse the order of the environments (or of the figure environment and the command):

\begin{figure}
  \begin{tabular}{|l|}
    \hline
    \includegraphics{foo}
    \caption{A foo}
    \hline
  \end{tabular}
\end{figure}

The same goes for table environments (or any other sort of float you’ve defined for yourself) inside tabulars or box commands; you must get the float environment out from inside, one way or another.

FAQ ID: Q-parmoderr
Last updated: 2018-05-27