Underfull \hbox (badness 10000) in paragraph within nested minipages

Question

I am generating a PDF using a .tex file of similar name.

Generating the PDF with pdflatex generates a number of Underfull \hbox (badness 10000) in paragraph at lines 539--542, with each set of line numbers referring to a minipage block.

      \begin{minipage}{\columnwidth}
        \vskip 1ex\textbf{GenZoom Recovery\hfill\begin{minipage}{\dimexpr\linewidth-27ex\relax}\raggedleft \mbox{6:30PM}\end{minipage}}
        Zoom-Only\hfill WA\\{\6pt
        We meet daily for quick and short meetings to help each other through the work day.}
      \end{minipage}
      \begin{minipage}{\columnwidth}
        \vskip 1ex\textbf{Broken Meeting No.1\hfill\begin{minipage}{\dimexpr\linewidth-27ex\relax}\raggedleft \mbox{6:30PM}\end{minipage}}
        Guiding Schoolhouse\hfill WA\\
        567 Beacon Lane, Nurtureville, NV, 89007
      \end{minipage}

I suspect this has to do with using a minipage inside of a minipage in order to get times/tags aligned to the right side. I read that trailing/unused \\ can cause these warnings, but removing them didn't seem to produce any change.

Full example, as requested:

\documentclass[11pt,twoside,letterpaper]{article}
\usepackage[utf8]{inputenc}
\usepackage[letterpaper,margin=0.25in]{geometry}
\setlength{\parindent}{0em}
\setlength{\parskip}{1ex}
\usepackage{anyfontsize}
\usepackage{mathptmx}
\usepackage{multicol}
\usepackage{microtype}
\usepackage{graphicx}
\usepackage{enumitem}

\def\6pt{\fontsize{6}{7.2}\selectfont}
\def\7pt{\fontsize{7}{8}\selectfont}
\def\8pt{\fontsize{8.5}{10}\selectfont}
\def\gutter{\hspace{0.02\textwidth}}

\fontfamily{phv}\fontseries{mc}\selectfont
\begin{document}

  {\textbf{Meetings}}\hrulefill\vskip 1ex
  \begin{multicols}{4}
    
    \vskip 2ex{\8pt\textbf{Sunday}}\hrulefill\vskip 1ex
    {\7pt
      \begin{minipage}{\columnwidth}
        \vskip 1ex\textbf{Serenity Path AA\hfill\begin{minipage}{\dimexpr\linewidth-27ex\relax}\raggedleft \mbox{6:30PM}\end{minipage}}\\
        Harmony Church\hfill WA\\
        345 Ascend Street, Serenity Springs, NV, 89007\\
      \end{minipage}
      \begin{minipage}{\columnwidth}
        \vskip 1ex\textbf{GenZoom Recovery\hfill\begin{minipage}{\dimexpr\linewidth-27ex\relax}\raggedleft \mbox{6:30PM}\end{minipage}}\\
        Zoom-Only\hfill WA\\{\6pt
        We meet daily for quick and short meetings to help each other through the work day.}
      \end{minipage}
    }
  \end{multicols}
  

\end{document}

Answer 1

I can explain you why there are two Underfull \hbox warnings when your full example is processed.

Underfull \hbox (badness 10000) in paragraph at lines 27--30


Underfull \hbox (badness 10000) in paragraph at lines 26--37

First one is due to your bad \\ at the end of line 29. The \\ is defined as \hfil\break in this context and this creates empty line in the paragraph which is underfull. More exact explanation needs to understand deeply the paragraph breaking algorithm in TeX, it is not only for short explanation. The main message is: the paragraph cannot end by \\.

The second Underfull message is here because you have four columns declared by \begin{multicols} but only material for three columns is available. If you add a line before \end{multicols} with something, for example:

   ...
   }
  something
  \end{multicols}
  ...

then the second Underfull message disappear.

Note that if you define

\def\6pt{...}

then you don't define the control sequence \6pt but only the control sequence \6 which is macro with the obligatory parameter pt. It works in your case but it seems that there is misunderstanding how TeX tokenizer works and how macros are defined.

Answer 2

You have \\ at the end of a paragraph generating an underful box, but more generally the multicols and nested minipages are not helping. If you simplfy the markup it is easier to avoid empty boxes.

\documentclass[11pt,twoside,letterpaper]{article}
\usepackage[utf8]{inputenc}
\usepackage[letterpaper,margin=0.25in]{geometry}
\setlength{\parindent}{0em}
\setlength{\parskip}{1ex}
\usepackage{anyfontsize}
\usepackage{mathptmx}
\usepackage{multicol}
\usepackage{microtype}
\usepackage{graphicx}
\usepackage{enumitem}

\def\sixpt{\fontsize{6}{7.2}\selectfont}
\def\sevenpt{\fontsize{7}{8}\selectfont}
\def\eightpt{\fontsize{8.5}{10}\selectfont}
\def\gutter{\hspace{0.02\textwidth}}

\fontfamily{phv}\fontseries{mc}\selectfont
\begin{document}


\textbf{Meetings}\hrulefill\vspace{1ex}

    
\sevenpt
\begin{minipage}[t]{.235\columnwidth}
    \eightpt\textbf{Sunday}\hrulefill
\end{minipage}\gutter
\begin{minipage}[t]{.235\columnwidth}
\textbf{Serenity Path AA\hfill 6:30PM}\par
        Harmony Church\hfill WA\par
\sixpt  345 Ascend Street, Serenity Springs, NV, 89007
\end{minipage}\gutter
\begin{minipage}[t]{.235\columnwidth}
\textbf{GenZoom Recovery\hfill 6:30PM}\par
        Zoom-Only\hfill WA\par
\sixpt    We meet daily for quick and short meetings to help each other through the work day.
\end{minipage}



  

\end{document}

Answer 3

Do define commands for such jobs!

You don't need nested minipages and guesswork about the spacing. The following accommodates three meetings per line, if more are on some day they're set under the others.

\documentclass[11pt,twoside,letterpaper]{article}
%\usepackage[utf8]{inputenc} % <-- no longer needed
\usepackage[letterpaper,margin=0.25in]{geometry}

%\usepackage{anyfontsize}% <-- obsolete and useless with mathptmx
\usepackage{mathptmx}
%\usepackage{multicol}% <-- not needed
\usepackage{microtype}

\newcommand{\sixpt}{\fontsize{6}{7.2}\selectfont}
\newcommand{\sevenpt}{\fontsize{7}{8}\selectfont}
\newcommand{\eightpt}{\fontsize{8.5}{10}\selectfont}

\newcommand{\gutter}{1em}
\newcommand{\WIDTH}{\dimeval{(\textwidth-\dimeval{\gutter}*3)/4}}

\newcommand{\DAY}[1]{%
  \par\addvspace{2ex}%
  \hspace*{-\leftskip}%
  \makebox[\WIDTH][l]{\eightpt\bfseries #1\hrulefill}%
  \hspace{\gutter}\ignorespaces
}
\newcommand{\MEETING}[5]{%
  \begin{minipage}[t]{\WIDTH}
  \setlength{\lineskip}{1pt}
  \sevenpt
  {\bfseries #1\hfill #2\par}
  {#3\hfill #4\par}
  #5
  \end{minipage}\hspace{\gutter plus 2pt minus 2pt}\ignorespaces
}

\setlength{\parindent}{0em}
\AtBeginDocument{%
  \setlength{\leftskip}{\dimeval{\WIDTH+\gutter}}%
  \setlength{\lineskip}{1ex}%
}

%\fontfamily{phv}\fontseries{mc}\selectfont % <-- does nothing at all

\begin{document}

\hspace*{-\leftskip}\textbf{Meetings}\hrulefill

\vspace{1ex}
    
\DAY{Sunday}
\MEETING{Serenity Path AA}{6:30PM}{Harmony Church}{WA}{
  345 Ascend Street, Serenity Springs, NV, 89007
}
\MEETING{GenZoom Recovery}{6:30PM}{Zoom-Only}{WA}{
  \sixpt
   We meet daily for quick and short meetings to help each other through the work day.
}

\DAY{Monday}
\MEETING{Serenity Path AA}{6:30PM}{Harmony Church}{WA}{
  345 Ascend Street, Serenity Springs, NV, 89007
}
\MEETING{GenZoom Recovery}{6:30PM}{Zoom-Only}{WA}{
  \sixpt
   We meet daily for quick and short meetings to help each other through the work day.
}
\MEETING{GenZoom Recovery}{6:30PM}{Zoom-Only}{WA}{
  \sixpt
   We meet daily for quick and short meetings to help each other through the work day.
}

\DAY{Tuesday}
\MEETING{Serenity Path AA}{6:30PM}{Harmony Church}{WA}{
  345 Ascend Street, Serenity Springs, NV, 89007
}
\MEETING{Serenity Path AA}{6:30PM}{Harmony Church}{WA}{
  345 Ascend Street, Serenity Springs, NV, 89007
}
\MEETING{GenZoom Recovery}{6:30PM}{Zoom-Only}{WA}{
  \sixpt
   We meet daily for quick and short meetings to help each other through the work day.
}
\MEETING{GenZoom Recovery}{6:30PM}{Zoom-Only}{WA}{
  \sixpt
   We meet daily for quick and short meetings to help each other through the work day.
}

\end{document}

The gutter between columns is parameterized so you can change it in a single place. The column widths are computed accordingly.

Please, check the <-- tags in the code and remove those parts. For instance, anyfontsize is obsolete and useless anyway when you load scalable fonts such as those provided by mathptmx.

Note that \def\6pt{...} is accepted by TeX, but I cannot recommend using it.

Answer 4

Welcome to TeX.SE!

Edit:

• Thank you for editing question.
• Provided document example works doesn't generate any warnings, however throw two bad boxes.
• Your code in is unnecessary complicated.
• In my MWE below I remove all \mboxes and nested mini pages.
• So, MWE which not produce your problem, can be:

\documentclass[11pt,twoside,letterpaper]{article}

\usepackage[letterpaper,margin=0.25in]{geometry}
\setlength{\parindent}{0em}     % <----
\setlength{\parskip}{1ex}
\usepackage{anyfontsize}
\usepackage{mathptmx}
\usepackage{multicol}
\usepackage{microtype}
\usepackage{graphicx}
\usepackage{enumitem}

\def\6pt{\fontsize{6}{7.2}\selectfont}
\def\7pt{\fontsize{7}{8}\selectfont}
\def\8pt{\fontsize{8.5}{10}\selectfont}
\def\gutter{\hspace{0.02\textwidth}}

\fontfamily{phv}
\fontseries{mc}\selectfont
\begin{document}
Nunc sed pede. Praesent vitae lectus. Praesent neque justo, vehicula eget, interdum id, facilisis et, nibh. Phasellus at purus et libero lacinia dictum. Fusce aliquet. Nulla eu ante placerat leo semper dictum. Mauris metus. Curabitur lobortis. Curabitur sollicitudin hendrerit nunc. Donec ultrices lacus id ipsum.

\textbf{Meetings}\hrulefill

\vskip 1ex
\begin{multicols}{4}
\vskip 2ex
\begin{minipage}[t]{\linewidth}\8pt
\textbf{Sunday}             \hrulefill
\end{minipage}
\begin{minipage}[t]{\linewidth}\7pt
\textbf{Serenity Path AA}   \hfill 6:30PM   \\
Harmony Church              \hfill WA       \\
345 Ascend Street, Serenity Springs, NV, 89007 
\end{minipage}
\begin{minipage}[t]{\linewidth}
\textbf{GenZoom Recovery}   \hfill 6:30PM   \\
Zoom-Only                   \hfill WA       \\
\6pt
We meet daily for quick and short meetings to help each other through the work day.
\end{minipage}
  \end{multicols}
\end{document}

It not produce any warnings nor bad boxes

BTW, are you sure that you need for columns? Are for your example are not sufficient just three?