Rendering PDFs with rmarkdown requires a working LaTeX installation, such as tinytex. Occasionally, existing workflows break with the newest version of LaTeX. This post describes how to run an older LaTeX version for just a little while.

Rendering PDFs with rmarkdown requires a working LaTeX installation. The excellent tinytex package helps installing a portable variant of the TeXlive distribution with minimal fuss, on any major operating system. It is really as simple as:

tinytex::install_tinytex()
        
trying URL 'https://yihui.org/tinytex/TinyTeX-1.tgz'
        Content type 'application/octet-stream' length 87001665 bytes (83.0 MB)
        

Breaking changes in LaTeX?

Despite its age, LaTeX is still a lively maintained and evolving system, with the consequence that some documents that worked on an older version of LaTeX may no longer work with the most recent stack. One such example is the tabu package that breaks for some use cases with TeXlive 2021.

On a clean tinytex installation, rendering an .rmd document with the following code starts with installing missing packages:

knitr::kable(mtcars, booktabs = TRUE, longtable = TRUE) |>
        kableExtra::kable_styling(full_width = TRUE)
        
tlmgr: package repository https://mirror.foobar.to/CTAN/systems/texlive/tlnet (not verified: gpg unavailable)
        [1/1, ??:??/??:??] install: multirow [3k]
        running mktexlsr ...
        done running mktexlsr.
        tlmgr: package log updated: ~/Library/TinyTeX/texmf-var/web2c/tlmgr.log
        tlmgr: command log updated: ~/Library/TinyTeX/texmf-var/web2c/tlmgr-commands.log
        tlmgr: package repository https://mirror.foobar.to/CTAN/systems/texlive/tlnet (not verified: gpg unavailable)
        [1/1, ??:??/??:??] install: wrapfig [10k]
        running mktexlsr ...
        ...
        

Yes, missing packages are installed on the fly! A full LaTeX distribution has several GB in size. The lazy package installation is a cool feature of the tinytex distribution that allows starting quickly with a minimal installation, without downloading and unpacking the whole thing.

However, compilation gives the following error message:

tlmgr: package log updated: ~/Library/TinyTeX/texmf-var/web2c/tlmgr.log
        tlmgr: command log updated: ~/Library/TinyTeX/texmf-var/web2c/tlmgr-commands.log
        ! Dimension too large.
        \LT@max@sel #1#2->{\ifdim #2=\wd \tw@ 
        #1\else \number \c@LT@chunks \fi }{\th...
        l.317 \end{longtabu}
        Error: LaTeX failed to compile test.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See test.log for more info.
        

What if we switch to the previous version?

“But it used to work yesterday!” Fine, let’s install the last version that is still based on TeXlive 2020:

tinytex::install_tinytex(version = "2021.03")
        

Unfortunately, this breaks the package downloader:

A new version of TeX Live has been released. If you need to install or update any LaTeX packages, you have to upgrade TinyTeX with tinytex::reinstall_tinytex(). If it fails to upgrade, you might be using a default random CTAN mirror that has not been fully synced to the main CTAN repository, and you need to wait for a few more days or use a CTAN mirror that is known to be up-to-date (see the "repository" argument on the help page ?tinytex::install_tinytex).
        tlmgr: Local TeX Live (2020) is older than remote repository (2021).
        Cross release updates are only supported with
        update-tlmgr-latest(.sh/.exe) --update
        See https://tug.org/texlive/upgrade.html for details.
        ! LaTeX Error: File `multirow.sty' not found.
        ...
        

And we’re told to upgrade TeXlive, which isn’t helpful in our particular use case.

Can we make the previous version work?

Yes. The solution is to teach tinytex to make do with a historic snapshot of the TeXlive distribution:

tinytex::tlmgr("option repository https://ftp.tu-chemnitz.de/pub/tug/historic/systems/texlive/2020/tlnet-final")
        
tlmgr: setting default package repository to https://ftp.tu-chemnitz.de/pub/tug/historic/systems/texlive/2020/tlnet-final
        tlmgr: updating ~/Library/TinyTeX/tlpkg/texlive.tlpdb
        

After that, automatic package downloads work again, with a prominent message reminding you that you’re running on a frozen snapshot:

knitr::kable(mtcars, booktabs = TRUE, longtable = TRUE) |>
        kableExtra::kable_styling(full_width = TRUE)
        
TeX Live 2020 is frozen and will no longer
        be routinely updated. This happens in preparation for a new release.
        If you're willing to help with pretesting the new release, and we hope
        you are, (when pretests are available), please read
        https://tug.org/texlive/pretest.html.
        Otherwise, just wait, and the new release will be ready in due time.
        TeX Live 2020 is frozen and will no longer
        be routinely updated. This happens in preparation for a new release.
        If you're willing to help with pretesting the new release, and we hope
        you are, (when pretests are available), please read
        https://tug.org/texlive/pretest.html.
        Otherwise, just wait, and the new release will be ready in due time.
        tlmgr: package repository https://ftp.tu-chemnitz.de/pub/tug/historic/systems/texlive/2020/tlnet-final (not verified: gpg unavailable)
        [1/1, ??:??/??:??] install: multirow [3k]
        running mktexlsr ...
        done running mktexlsr.
        tlmgr: package log updated: /Users/kirill/Library/TinyTeX/texmf-var/web2c/tlmgr.log
        TeX Live 2020 is frozen and will no longer
        be routinely updated. This happens in preparation for a new release.
        ...
        

The document is now rendered without errors.

The tinytex maintainers have confirmed that old bundles remain available for download. Of course the correct solution is to avoid weakly maintained dependencies in your code, and to replace them by better solutions. In reality, this is not always feasible, and breakages may occur without notice.

Happy freezing!

Details

On the TeXlive homepage, the “How to acquire TeX Live: other methods” link has a section “Past releases”. The tlmgr command is shown right there. The “Historic archive” page contains a list of historic mirrors, use a mirror close to you.

I originally started my search at the “Historic archive” page. It took some time to find the correct command, it is also documented in the tlmgr manual.