Q: labelfont=bf option not found in caption.sty After updating to the latest version of MacTeX and TeXmaker, I'm unable to use bold fonts within the caption package for only one of my LaTeX documents. All other documents allow this without complaint.
Specifically, within the preamble of all my documents I have
\usepackage[labelfont=bf]{caption}

but upon compiling for the problematic document, receive the error message
Unknown option `labelfont=bf` for package `caption`

The error directs me to line 78 of caption.sty
\newsavebox{\as@captionbox}

I've tried as per the CTAN documentation
\usepackage[labelfont=bf]{caption}[2020/09/12]

\usepackage{caption}
\captionsetup{labelfont=bf}

and also including \captionsetup{...} within the figure environments themselves.
Line 78 of my .tex has no reference to figures and only includes text in math mode \tt and \textit
When I try to recreate the error via an MRE, the error disappears.
For instance
\documentclass[12pt]{article}
\usepackage[labelfont=bf]{caption}
\UseRawInputEncoding

\begin{document}

\begin{figure}[H]
    \caption{Lorem ipsum dolor}
\end{figure}

\end{document}

This question is similar, but for a different purpose
\labelfont from caption package not working
EDIT
Review of my log file reveals the following regarding \newsavebox{\as@captionbox}
Package: caption v1.4b <1995/04/05> (Harald Sommerfeldt)
\captionmargin=\skip56

! LaTeX Error: Unknown option `labelfont=bf' for package `caption'.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                              
l.78 \newsavebox
            {\as@captionbox}
The option `labelfont=bf' was not declared in package `caption', perhaps you
misspelled its name. Try typing  <return>  to proceed.

Here is my file list
*File List*
 article.cls    2020/04/10 v1.4m Standard LaTeX document class
 size12.clo    2020/04/10 v1.4m Standard LaTeX file (size option)
 amssymb.sty    2013/01/14 v3.01 AMS font symbols
 amsfonts.sty    2013/01/14 v3.01 Basic AMSFonts support
 amsmath.sty    2020/09/23 v2.17i AMS math features
 amstext.sty    2000/06/29 v2.01 AMS text
  amsgen.sty    1999/11/30 v2.0 generic functions
  amsbsy.sty    1999/11/29 v1.2d Bold Symbols
  amsopn.sty    2016/03/08 v2.02 operator names
      bm.sty    2019/07/24 v1.2d Bold Symbol Support (DPC/FMi)
   color.sty    1999/02/16
   color.cfg    2016/01/02 v1.6 sample color configuration
  pdftex.def    2020/10/05 v1.2a Graphics/color driver for pdftex
   float.sty    2001/11/08 v1.3d Float enhancements (AL)
graphicx.sty    1999/02/16 v1.0f Enhanced LaTeX Graphics (DPC,SPQR)
  keyval.sty    2014/10/28 v1.15 key=value parser (DPC)
graphics.sty    2020/08/30 v1.4c Standard LaTeX Graphics (DPC,SPQR)
    trig.sty    2016/01/03 v1.10 sin cos tan (DPC)
graphics.cfg    2016/06/04 v1.11 sample graphics configuration
mathtools.sty    2021/03/18 v1.25 mathematical typesetting tools
    calc.sty    2017/05/25 v4.3 Infix arithmetic (KKT,FJ)
 mhsetup.sty    2021/03/18 v1.4 programming setup (MH)
hyphenat.sty    2009/09/02 v2.3c hyphenation utilities
indentfirst.sty    1995/11/23 v1.03 Indent first paragraph (DPC)
 caption.sty    1995/04/05 v1.4b caption package (HS)
geometry.sty    2020/01/02 v5.9 Page Geometry
  ifvtex.sty    2019/10/25 v1.7 ifvtex legacy package. Use iftex instead.
   iftex.sty    2020/03/06 v1.0d TeX engine tests
tcolorbox.sty    2020/10/09 version 4.42 text color boxes
     pgf.sty    2020/12/27 v3.1.8b (3.1.8b)
  pgfrcs.sty    2020/12/27 v3.1.8b (3.1.8b)
pgfrcs.code.tex
 pgfcore.sty    2020/12/27 v3.1.8b (3.1.8b)
  pgfsys.sty    2020/12/27 v3.1.8b (3.1.8b)
pgfsys.code.tex
pgfsyssoftpath.code.tex    2020/12/27 v3.1.8b (3.1.8b)
pgfsysprotocol.code.tex    2020/12/27 v3.1.8b (3.1.8b)
  xcolor.sty    2016/05/11 v2.12 LaTeX color extensions (UK)
   color.cfg    2016/01/02 v1.6 sample color configuration
pgfcore.code.tex
pgfcomp-version-0-65.sty    2020/12/27 v3.1.8b (3.1.8b)
pgfcomp-version-1-18.sty    2020/12/27 v3.1.8b (3.1.8b)
verbatim.sty    2020-07-07 v1.5u LaTeX2e package for verbatim enhancements
 environ.sty    2014/05/04 v0.3 A new way to define environments
trimspaces.sty    2009/09/17 v1.1 Trim spaces around a token list
etoolbox.sty    2020/10/05 v2.5k e-TeX tools for LaTeX (JAW)
  lineno.sty    2005/11/02 line numbers on paragraphs v4.41
setspace.sty    2011/12/19 v6.7a set line spacing
  natbib.sty    2000/07/24 7.0a (PWD)
textcomp.sty    2020/02/02 v2.0n Standard LaTeX package
  lscape.sty    2020/05/28 v3.02 Landscape Pages (DPC)
footmisc.sty    2011/06/06 v5.5b a miscellany of footnote facilities
boxedminipage.sty    2020/04/19 v1.1 Boxed LaTeX2e minipages
l3backend-pdftex.def    2021-03-18 L3 backend support: PDF output (pdfTeX)
supp-pdf.mkii
epstopdf-base.sty    2020-01-24 v2.11 Base part for package epstopdf
epstopdf-sys.cfg    2010/07/13 v1.3 Configuration of (r)epstopdf for TeX Live
    umsa.fd    2013/01/14 v3.01 AMS symbols A
    umsb.fd    2013/01/14 v3.01 AMS symbols B
  omscmr.fd    2019/12/16 v2.5j Standard LaTeX font definitions
Figure S1.png    Graphic file (type png)
Figure S2.png    Graphic file (type png)
Figure S3.png    Graphic file (type png)
Figure S5.png    Graphic file (type png)
Figure S4.png    Graphic file (type png)
Figure S6.png    Graphic file (type png)
 ***********

