Solved: "Outdated pdfTeX in TeX Live/CTAN"

Dear Max,

thanks for your quick and thorough reply.
You were completely right. I did not successfully clean an older TeX Live installation; there were some files left in /usr/bin/, among them an old version of pdfTeX which was being prioritized. Since removing the old files, everything runs without error.

That also resolves my personal need for an error chain reconstruction. But for transparency: the /path/to/ is just a folder in my home directory.

I learned more about Linux and the TeX project.
Thank you,
Sly


In reply to: Max Chernoff <[email protected]>
> Hi Sly,
> 
> On Sat, 2025-10-18 at 23:09 +0000, slycape via pdftex wrote:
> 
> > I installed TeX Live 2025 the native way with 'full' scheme on Linux
> > x86_64. I made sure that everything is up-to-date according to tlmgr.
> > 
> > Nevertheless, pdfTeX is still not the current version listed at
> > https://tug.org/applications/pdftex/NEWS but instead the old version
> > 'pdfTeX 3.141592653-2.6-1.40.25 (TeX Live 2023)'.
> 
> 
> I'm guessing that you're using the wrong pdfTeX. What do you get when
> you run the following command:
> 
> $ type -ap pdftex | xargs -I@ sh -c 'echo @; @ --version'
> 
> Ideally that should only print a single path to pdfTeX, but as long as
> the newest (2025) version shows up first, you should be okay.
> 
> > Searching on CTAN also shows the package has last been changed in
> > August 2023.
> 
> 
> The catalogue entry (the metadata for the package) was last updated in
> August 2023, but the package contents were last updated some time in
> mid-February. CTAN doesn't actually show when a package's contents were
> last updated, but the "User Manual" link shows the date.
> 
> But pdfTeX is developed directly in TeX Live, and CTAN only copies the
> manual (and nothing else) from TL, so this mostly shouldn't matter.
> 
> > When runnning pdflatex, I get the following error message:
> > 
> > > ---! path/to/texlive/2025/texmf-var/web2c/pdftex/pdflatex.fmt made by different executable version, strings are different
> > > (Fatal format file error; I'm stymied)
> 
> 
> The value of "path/to/texlive" is probably important for debugging here,
> so can you please reply with that?
> 
> (But even if you had multiple versions of pdfTeX in your $PATH, fmtutil
> should only ever touch the format files corresponding to that instance
> of fmtutil/pdfTeX, so this error shouldn't be possible in the first
> place. Karl?)
> 
> > I believe this is due to the outdated package.
> 
> 
> Probably not.
> 
> > I am a newbie and don't know a workaround/manual way to update
> 
> 
> 1. Delete any user-local format files:
> 
> $ rm -rf ~/.texlive202*/texmf-var/web2c/
> 
> 2. Rebuild all the format files:
> 
> $ sudo $(type -p fmtutil-sys) --all
> 
> Hopefully that fixes everything, but if not, reply with the output of
> the above command (only the last dozen lines should be necessary) and
> we'll try to figure something out.
> 
> Thanks,
> -- Max