two identical .tex files; one compiles, one does not

Christopher W. Ryan cryan at
Mon Nov 21 18:19:41 CET 2022

For both files, I just used the "pdf" toolbar button in emacs. I used it
the same way for both files. I believe it is set to execute pdflatex. I
have emacs 26.2 from Vince Goulet, that has AUCTEX and ESS included.


--Chris Ryan

Julius Müller wrote:
> Did you use latex (for example pdflatex or lualatex or xelatex) with
> both files? If you did try tex (for example pdftex or luatex or xetex)
> on File1, the message would be totally OK: \documentclass is one of the
> macros defined in LaTeX but unknown to TeX.
> Am 21.11.22 um 17:58 schrieb Christopher W. Ryan via texhax:
>> I'm running texlive on Windows 10. I encountered the error message below
>> when attempting to compile a small letter. Let's say it is in File1.tex
>> ERROR: Undefined control sequence.
>> --- TeX said ---
>> l.1 \documentclass
>>                    {letter}
>> --- HELP ---
>> TeX encountered an unknown command name. You probably misspelled the
>> name. If this message occurs when a LaTeX command is being processed,
>> the command is probably in the wrong place---for example, the error
>> can be produced by an \item command that's not inside a list-making
>> environment. The error can also be caused by a missing \documentclass
>> command.
>> Here is my preamble:
>> \documentclass{letter}
>> \usepackage[vmargin=0.5in, hmargin = 1in]{geometry}
>> \address{SUNY Upstate Clinical Campus \\ PO Box 778 \\ Johnson City, NY
>> 13790 \\ US}
>> \signature{Christopher W. Ryan, MD, MS, MSPH}
>> Oddly, when I create an identical file, let's call it File2.tex, it
>> compiles just fine.  I compared the two files in Windows Total
>> Commander, and it tells me they have identical content.
>> I notice that compiling File1.tex, the problematic one, no .aux file is
>> created, whereas it is when compiling File2.tex
>> I have not seen this behavior before. Can anyone explain what is
>> happening?
>> Thanks.
>> --Chris Ryan

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