Problem with chemmacros, beamer and filehook-scrlfile.sty

The issue has been fixed in the last filehook update. An update to your LaTeX installation should resolve the issue. (Additionally, as Ulrike wrote, sansmathaccent had already been changed not to use filehook, which removed this particular incompatibility.)

---

As noted in the comments, the problem is that filehook-scrlfile has not been updated to work with the new definition of \InputIfFileExists in scrlfile. Until the author updates this file accordingly, as a workaround, you can place a file called filehook-scrlfile.sty with the following content in your compilation directory.

%% Modified version of filehook-scrlfile as a workaround.
%% See https://tex.stackexchange.com/a/515183/48973.
%%
\NeedsTeXFormat{LaTeX2e}[1999/12/01]
\ProvidesPackage{filehook-scrlfile}[2011/01/03 v0.1 filehook patch for scrlfile package]
\RequirePackage{filehook}
\begingroup
\long\def\scrlfile@InputIfFileExists#1#2{%
  \begingroup\expandafter\expandafter\expandafter\endgroup
  \expandafter\ifx\csname #1-@alias\endcsname\relax
    \expandafter\@secondoftwo
  \else
    \scr@replacefile@msg{\csname #1-@alias\endcsname}{#1}%
    \expandafter\@firstoftwo
  \fi
  {%
    \expandafter\InputIfFileExists\expandafter{\csname
      #1-@alias\endcsname}{#2}%
  }%
  {\IfFileExists{#1}{%
      \expandafter\scr@input@withhook\expandafter{\@filef@und}{#1}{#2}%
    }}%
}
\long\def\filehook@scrlfile@InputIfFileExists#1#2{%
  \begingroup\expandafter\expandafter\expandafter\endgroup
  \expandafter\ifx\csname #1-@alias\endcsname\relax
    \expandafter\@secondoftwo
  \else
    \scr@replacefile@msg{\csname #1-@alias\endcsname}{#1}%
    \expandafter\@firstoftwo
  \fi
  {%
    \expandafter\InputIfFileExists\expandafter{\csname
      #1-@alias\endcsname}{#2}%
  }%
  {\IfFileExists{#1}{%
      \expandafter\filehook@swap
      \expandafter{\@filef@und}%
      {\scr@load@hook{before}{#1}%
      #2\@addtofilelist{#1}%
      \filehook@every@atbegin{#1}%
      \filehook@atbegin{#1}%
      \@@input}%
      \filehook@atend{#1}%
      \filehook@every@atend{#1}%
      \scr@load@hook{after}{#1}%
    }}%
}
\long\def\filehook@@scrlfile@InputIfFileExists#1#2{%
  \let\InputIfFileExists\filehook@InputIfFileExists
  \begingroup\expandafter\expandafter\expandafter\endgroup
  \expandafter\ifx\csname #1-@alias\endcsname\relax
    \expandafter\@secondoftwo
  \else
    \scr@replacefile@msg{\csname #1-@alias\endcsname}{#1}%
    \expandafter\@firstoftwo
  \fi
  {%
    \expandafter\InputIfFileExists\expandafter{\csname
      #1-@alias\endcsname}{#2}%
  }%
  {\IfFileExists{#1}{%
      \expandafter\filehook@swap
      \expandafter{\@filef@und}%
      {\scr@load@hook{before}{#1}%
      #2\@addtofilelist{#1}%
      \filehook@atbegin{#1}%
      \@@input}%
      \filehook@atend{#1}%
      \scr@load@hook{after}{#1}%
    }}%
}
\ifcase
    \expandafter\ifx\csname InputIfFileExists \endcsname\latex@InputIfFileExists 0\else
    \expandafter\ifx\csname InputIfFileExists \endcsname\scrlfile@InputIfFileExists 0\else
     1%
    \fi\fi
\relax
  \global\let\filehook@InputIfFileExists\filehook@scrlfile@InputIfFileExists
  \global\let\filehook@@InputIfFileExists\filehook@@scrlfile@InputIfFileExists
  \global\expandafter\let\csname InputIfFileExists \endcsname\filehook@InputIfFileExists
  \PackageInfo{filehook}{Package 'scrlfile' detected and compensated for}%
\else
  \iffilehook@force
    \global\let\filehook@InputIfFileExists\filehook@default@InputIfFileExists
    \global\let\filehook@@InputIfFileExists\filehook@@default@InputIfFileExists
    \global\expandafter\let\csname InputIfFileExists \endcsname\filehook@InputIfFileExists
    \PackageWarning{filehook}{Detected 'scrlfile' package with unknown definition of \string\InputIfFileExists.^^J%
                              The 'force' option of 'filehook' is in effect. Macro is overwritten with default!}%
  \else
    \show\InputIfFileExists
    \expandafter\show\csname InputIfFileExists \endcsname
    \show\scrlfile@InputIfFileExists
    \PackageError{filehook}{Detected 'scrlfile' package with unknown definition of \string\InputIfFileExists.^^J%
                            Use the 'force' option of 'filehook' to overwrite it.}{}%
  \fi
\fi
\endgroup
\endinput
%%
%% End of file `filehook-scrlfile.sty'.

I am on a Windows 10 system using TeXstudio. I updated MiKTeX 2.9 on 1/9/2020 and still have the filehook error. By using the \PassOptionsToPackage{force}{filehook} command in my preamble, my \include commands are working again. I hope this may help someone.

The problem has been resolved by an update of the sansmathaccent package. It now no longer uses the filehook package.