Using \textuparrow I get the following error:

Package textcomp Error: Symbol \textuparrow not provided
by font family ppl in TS1 encoding. Default family used instead.


However, the arrows are drawn correctly, but with another font. How to get rid of the error message since it blocks latexml to run through?

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{mathpazo}
\usepackage{textcomp}

\begin{document}
\textuparrow
\end{document}


Redefine the command:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{mathpazo}
\usepackage{textcomp}

\renewcommand{\textuparrow}{$\uparrow$}

\begin{document}
\textuparrow
\end{document}


You can change the error into a warning by loading the package with the warn option.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{mathpazo}
\usepackage[warn]{textcomp}

\begin{document}
\textuparrow
\end{document}


The output is the same, you only receive the warning

Package textcomp Warning: Symbol \textuparrow not provided by
(textcomp)                font family ppl in TS1 encoding.
(textcomp)                Default family used instead on input line 8.


Upgrading to Ubuntu 20.04 from 18.04 worked for me. See https://github.com/borisveytsman/acmart/issues/74#issuecomment-590005846.