I recently uninstalled the apt version and switched to the tlmgr version (I think that's what it's called?) in an attempt to fix the issue.
My file is simply:
\documentclass{aricle}
\begin{document}
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
\end{document}
Running latex file.tex displays:
This is pdfTeX, Version 3.14159265-2.6-1.40.21 (TeX Live 2020) (preloaded format=latex)
restricted \write18 enabled.
entering extended mode
(./error.tex
LaTeX2e <2020-10-01> patch level 4
L3 programming layer <2021-01-09> xparse <2020-03-03>
! LaTeX Error: File `aricle.cls' not found.
Type X to quit or <RETURN> to proceed,
or enter new name. (Default extension: cls)
Enter file name: X
I get similar results with pdflatex, xelatex, and lualatex.
Despite all that, if I try to compile a (much larger) file on my dropbox it works just fine. Also if I write the exact same file in echo in the same directory it works:
$ echo '\documentclass{article}\begin{document}aaaaaaaaaaaaaaaaaaaaaaaaaaa\end{document}'| latex
This is pdfTeX, Version 3.14159265-2.6-1.40.21 (TeX Live 2020) (preloaded format=latex)
restricted \write18 enabled.
**entering extended mode
LaTeX2e <2020-10-01> patch level 4
L3 programming layer <2021-01-09> xparse <2020-03-03>
(/usr/local/texlive/2020/texmf-dist/tex/latex/base/article.cls
Document Class: article 2020/04/10 v1.4m Standard LaTeX document class
(/usr/local/texlive/2020/texmf-dist/tex/latex/base/size10.clo))
(/usr/local/texlive/2020/texmf-dist/tex/latex/l3backend/l3backend-dvips.def)
No file texput.aux.
[1] (./texput.aux)
Output written on texput.dvi (1 page, 272 bytes).
Transcript written on texput.log.
Running cat file | latex produces the same error as before, and concatenating the lines together doesn't help either.
It is a typo: you wrote \documentclass{aricle} instead of article.