For several days now I've had this error report showing when I'm building my pdf file -

====
! LaTeX Error: Command \gather already defined.
Or name \end... illegal, see p.192 of the manual.

See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...

l.1560 }
====

I don't have a latex manual or companion, and I just ignore the error report and proceed.

I'm not aware of any 'gather' package, nor what package is generating the error, so could someone please enlighten me as to how to correct the initial problem?

Thanks
Sharon.
--
Debian 11.5, fluxbox 1.3.7, emacs 29.0.50, org 9.5.5

Am Mon, 12 Dec 2022 15:33:01 +0000 schrieb Sharon Kimble:

> For several days now I've had this error report showing when I'm building my pdf file -
>
> ====
> ! LaTeX Error: Command \gather already defined.
> Or name \end... illegal, see p.192 of the manual.

Load the lineno package earlier (before amsmath).

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

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Hash: SHA512

Ulrike Fischer <news3@nililand.de> writes:

Thanks for replying.

> Am Mon, 12 Dec 2022 15:33:01 +0000 schrieb Sharon Kimble:
>
>> For several days now I've had this error report showing when I'm building my pdf file -
>>
>> ===>> ! LaTeX Error: Command \gather already defined.
>> Or name \end... illegal, see p.192 of the manual.
>
>
> Load the lineno package earlier (before amsmath).

But I'm not loading lineno nor amsmath in any of my setup files. Although I do see lineno being used in the log file. So if I'm not loading it, what is? Any ideas please?

Thanks
Sharon.
- --
Debian 11.5, fluxbox 1.3.7, emacs 29.0.50, org 9.5.5
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Am Tue, 13 Dec 2022 16:32:35 +0000 schrieb Sharon Kimble:

>> Load the lineno package earlier (before amsmath).
>
> But I'm not loading lineno nor amsmath in any of my setup files. Although I do see lineno being used in the log file. So if I'm not loading it, what is? Any ideas please?

how should I know? You don't show any code and so I made a wild
guess that the lineno change (which triggers this error) is the
cause.

If not you will have to show a complete, small example.

(And I got it wrong: if lineno is the problem, then you should load
it *after* amsmath).

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

On 12/12/2022 15:33, Sharon Kimble wrote:
> For several days now I've had this error report showing when I'm building my pdf file -
>
> ====
> ! LaTeX Error: Command \gather already defined.
> Or name \end... illegal, see p.192 of the manual.
>
> See the LaTeX manual or LaTeX Companion for explanation.
> Type H <return> for immediate help.
> ...
>
> l.1560 }
> ====
>
> I don't have a latex manual or companion, and I just ignore the error report and proceed.
>
> I'm not aware of any 'gather' package, nor what package is generating the error, so could someone please enlighten me as to how to correct the initial problem?
>
> Thanks
> Sharon.

Here are some strategies for diagnosing the problem.

Add \show followed by the name of the problematic command after each
instance of \usepackage. This will interrupt the document build and show
the definition of the command. Also add \listfiles to get a summary of
all loaded packages (including those that are implicitly loaded by other
packages).

For example:

\listfiles
\documentclass{article}
\show\gather
\usepackage{graphicx}
\show\gather
\usepackage{amsmath}
\show\gather

\begin{document}
Test
\end{document}

This will have the following lines in the transcript (interspersed with
other messages):

> \gather=undefined

> \gather=undefined.

> \gather=\long macro:
->\start@gather \st@rredfalse .

This indicates that the command has been defined between the second and
third instances of \show\gather, which is when amsmath is input. Comment
out the \usepackage line and try again to find the other package that's
defining the command.

It may not actually be a command. It could be an environment. It may
also not be defined by the package that you've loaded, but may be
defined by a dependent package.

Since you're using Debian, you can also use a combination of find and
grep to search for packages that may be defining the command. For example:

find `kpsewhich --var-value=TEXMFDIST` `kpsewhich
--var-value=TEXMFLOCAL` `kpsewhich --var-value=TEXMFHOME` \( -name
"*.sty" -o -name "*.cls" \) -exec grep -l -e '[\\{]gather\b[^@]' {} \;

Search the summary list at the end of the transcript (which is produced
by \listfiles) for any of the files that are found by grep. Once you've
worked out which packages are causing a conflict, then you can try
swapping the load order round to see if that helps or decide if you can
drop one of them or replace it with another package. At the very least
it can provide you with a minimum example that just loads those two
packages which you can post here.

Regards
Nicola Talbot
--
Dickimaw Books
Home: https://www.dickimaw-books.com/
Creating a LaTeX Minimal Example:
https://www.dickimaw-books.com/latex/minexample/
LaTeX Resources: https://www.dickimaw-books.com/latexresources.html

Hi Sharon

It would be most helpful if you could upload the log file, up to the point at which the error occurs. From there I think the source of error could soon be found.

LaTeX wrote:
> ! LaTeX Error: Command \gather already defined.
> Or name \end... illegal, see p.192 of the manual.

In my opinion, it is unfortunate that LaTeX is not doing more to help you. In 1992 referring to page 192 of the manual is appropriate. In 2022 (nearly 2023) it is not.

By the way, is this a file that used to work, but since a few days ago does not?

with kind regards

Jonathan

Dne čtvrtek 15. prosince 2022 v 16:59:33 UTC+1 uživatel Jonathan Fine napsal:
> Hi Sharon
>
> It would be most helpful if you could upload the log file, up to the point at which the error occurs. From there I think the source of error could soon be found.
> LaTeX wrote:
> > ! LaTeX Error: Command \gather already defined.
> > Or name \end... illegal, see p.192 of the manual.
> In my opinion, it is unfortunate that LaTeX is not doing more to help you.. In 1992 referring to page 192 of the manual is appropriate. In 2022 (nearly 2023) it is not.
>
> By the way, is this a file that used to work, but since a few days ago does not?
>
> with kind regards
>
> Jonathan
I have same problem like Sheron describes. The problems occurred after a major update to my Miktex package. I think it's a deeper bug and that it's not due to the order of the libraries in the source file.

Am Fri, 16 Dec 2022 08:20:08 -0800 (PST) schrieb Jaroslav Fait:

> I have same problem like Sheron describes. The problems occurred
> after a major update to my Miktex package. I think it's a deeper
> bug and that it's not due to the order of the libraries in the
> source file.

Personally I'm quite willing to bet that is due to the order of
packages as I ran into the same error after the update but if you
think otherwise: provide a complete example and the log file so that
one debug your problem.

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

Am Thu, 15 Dec 2022 07:59:29 -0800 (PST) schrieb Jonathan Fine:

>> ! LaTeX Error: Command \gather already defined.
>> Or name \end... illegal, see p.192 of the manual.
> In my opinion, it is unfortunate that LaTeX is not doing more to
> help you. In 1992 referring to page 192 of the manual is
> appropriate. In 2022 (nearly 2023) it is not.

p.192 is at least exact and fix. Any other link would not be stable,
and you can't add a label/ref into such a message. So the only way
to change this would be to drop the "see part", which doesn't
really help much more.

Beside this: Changing error messages affects lots of test files, and
also various scripts in external tools scanning the log for errors.
So we typically avoid to change much here.

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

Jaroslav Fait schrieb am Freitag, 16. Dezember 2022 um 16:20:11 UTC:
> I have same problem like Sheron describes. The problems occurred after a major update to my Miktex package. I think it's a deeper bug and that it's not due to the order of the libraries in the source file.

I think so too. I have been working with my document for many months. Haven't changed anything significant, but now also get this error after I updated my LaTeX packages last (11/12/2022) or before last Sunday (04/12/2022).

Max M schrieb am Samstag, 17. Dezember 2022 um 12:28:52 UTC:
> Jaroslav Fait schrieb am Freitag, 16. Dezember 2022 um 16:20:11 UTC:
> > I have same problem like Sheron describes. The problems occurred after a major update to my Miktex package. I think it's a deeper bug and that it's not due to the order of the libraries in the source file.
> I think so too. I have been working with my document for many months. Haven't changed anything significant, but now also get this error after I updated my LaTeX packages last (11/12/2022) or before last Sunday (04/12/2022).

I have restored an older version (4.41) of the lineno package and the error messages have disappeared. I have not included the lineno package myself, but I think it is used by e.g. minted (\setminted{linenos}).

Am Sat, 17 Dec 2022 04:48:54 -0800 (PST) schrieb Max M:

> I have restored an older version (4.41) of the lineno package and
> the error messages have disappeared. I have not included the
> lineno package myself, but I think it is used by e.g. minted
> (\setminted{linenos}).

Simply load lineno later (or amsmath earlier).

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

Ulrike Fischer schrieb am Samstag, 17. Dezember 2022 um 15:18:54 UTC:
> Am Sat, 17 Dec 2022 04:48:54 -0800 (PST) schrieb Max M:
>
>
> > I have restored an older version (4.41) of the lineno package and
> > the error messages have disappeared. I have not included the
> > lineno package myself, but I think it is used by e.g. minted
> > (\setminted{linenos}).
> Simply load lineno later (or amsmath earlier).
> --
> Ulrike Fischer
> http://www.troubleshooting-tex.de/

I do not load lineno or amsmath. Another package must load that.

Am Mon, 19 Dec 2022 01:03:48 -0800 (PST) schrieb Max M:

> I do not load lineno or amsmath. Another package must load that.

Of course, if they are loaded, then because someone are loading
them.

Add \RequirePackage{structuredlog} before documentclass, then check
the log. It should be rather easy to find out where the packages
are loaded.

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

Ulrike Fischer schrieb am Montag, 19. Dezember 2022 um 11:57:48 UTC:
> Am Mon, 19 Dec 2022 01:03:48 -0800 (PST) schrieb Max M:
>
> > I do not load lineno or amsmath. Another package must load that.
> Of course, if they are loaded, then because someone are loading
> them.
>
> Add \RequirePackage{structuredlog} before documentclass, then check
> the log. It should be rather easy to find out where the packages
> are loaded.
> --
> Ulrike Fischer
> http://www.troubleshooting-tex.de/

Thank you.

I have moved minted to amsmath. No error occurs any more. But this cannot be the solution to the problem, because a) it worked with an older version of lineno (< 5.0) and b) there are other packages whose order is important. This is not user-friendly and at some point it becomes very confusing, because I have already imported 7 packages whose tyre sequence must be observed..

Am Mon, 19 Dec 2022 05:21:42 -0800 (PST) schrieb Max M:

> Thank you.
>
> I have moved minted to amsmath. No error occurs any more. But
> this cannot be the solution to the problem, because a) it worked
> with an older version of lineno (< 5.0) and b) there are other
> packages whose order is important. This is not user-friendly and
> at some point it becomes very confusing, because I have already
> imported 7 packages whose tyre sequence must be observed.

I quite agree that this should done better, and there is already an
open issue:

https://github.com/latex-lineno/lineno/issues/5

As you can see, we (the latex team, in this case Frank) are trying
to resolve the problem.

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

Ulrike Fischer schrieb am Montag, 19. Dezember 2022 um 22:53:09 UTC:
> Am Mon, 19 Dec 2022 05:21:42 -0800 (PST) schrieb Max M:
>
> > Thank you.
> >
> > I have moved minted to amsmath. No error occurs any more. But
> > this cannot be the solution to the problem, because a) it worked
> > with an older version of lineno (< 5.0) and b) there are other
> > packages whose order is important. This is not user-friendly and
> > at some point it becomes very confusing, because I have already
> > imported 7 packages whose tyre sequence must be observed.
> I quite agree that this should done better, and there is already an
> open issue:
>
> https://github.com/latex-lineno/lineno/issues/5
>
> As you can see, we (the latex team, in this case Frank) are trying
> to resolve the problem.
> --
> Ulrike Fischer
> http://www.troubleshooting-tex.de/

Thank you very much for your commitment! 🙏

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Hash: SHA512

> Jonathan Fine <jfine2358@gmail.com> writes:

> Hi Sharon
>
> It would be most helpful if you could upload the log file, up to the point at which the error occurs. From there I think the source of error could soon be found.
>
> LaTeX wrote:
>> ! LaTeX Error: Command \gather already defined.
>> Or name \end... illegal, see p.192 of the manual.
>
> In my opinion, it is unfortunate that LaTeX is not doing more to help you.. In 1992 referring to page 192 of the manual is appropriate. In 2022 (nearly 2023) it is not.

I've been able to get a secondhand copy of the 'The Latex Companion', 2nd edition, 2004 version. And page 192 is blank, and is on the left-hand side facing Chapter 4, The Layout of the Page.

So what manual is the error report referring to please?

Thanks
Sharon.
- --
Debian 11.5, fluxbox 1.3.7, emacs 29.0.60, org 9.5.5
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> Jaroslav Fait <jardak.fait@gmail.com> writes:

> Dne čtvrtek 15. prosince 2022 v 16:59:33 UTC+1 uživatel Jonathan Fine napsal:
>> Hi Sharon
>>
>> It would be most helpful if you could upload the log file, up to the point at which the error occurs. From there I think the source of error could soon be found.
>> LaTeX wrote:
>> > ! LaTeX Error: Command \gather already defined.
>> > Or name \end... illegal, see p.192 of the manual.
>> In my opinion, it is unfortunate that LaTeX is not doing more to help you. In 1992 referring to page 192 of the manual is appropriate. In 2022 (nearly 2023) it is not.
>>
>> By the way, is this a file that used to work, but since a few days ago does not?
>>
>> with kind regards
>>
>> Jonathan
> I have same problem like Sheron describes. The problems occurred after a major update to my Miktex package. I think it's a deeper bug and that it's not due to the order of the libraries in the source file.

I've found out where the problem is coming from, the package 'minted' is loading lineno and amsmath in the background. As I'm not using mathematical symbols, I've stopped using minted, and everything is now working nicely.

Thanks
Sharon.
- --
Debian 11.5, fluxbox 1.3.7, emacs 29.0.60, org 9.5.5
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On 26/12/2022 12:08, Sharon Kimble wrote:
>> Jonathan Fine <jfine2358@gmail.com> writes:
>
>> Hi Sharon
>
>> It would be most helpful if you could upload the log file, up to the point at which the error occurs. From there I think the source of error could soon be found.
>
>> LaTeX wrote:
>>> ! LaTeX Error: Command \gather already defined.
>>> Or name \end... illegal, see p.192 of the manual.
>
>> In my opinion, it is unfortunate that LaTeX is not doing more to help you. In 1992 referring to page 192 of the manual is appropriate. In 2022 (nearly 2023) it is not.
>
> I've been able to get a secondhand copy of the 'The Latex Companion', 2nd edition, 2004 version. And page 192 is blank, and is on the left-hand side facing Chapter 4, The Layout of the Page.
>
> So what manual is the error report referring to please?

That would be LaTeX: A Document Preparation System, by Leslie Lamport.
But I have to agree with Jonathan Fine that refering to a page in that
manual isn't particulary useful. I have my doubts if even in 1992 it was
useful.

On Monday, December 26, 2022 at 4:13:40 PM UTC-5, Eduardo M KALINOWSKI wrote:
> On 26/12/2022 12:08, Sharon Kimble wrote:
> >> Jonathan Fine <jfin...@gmail.com> writes:
> >
> >> Hi Sharon
> >
> >> It would be most helpful if you could upload the log file, up to the point at which the error occurs. From there I think the source of error could soon be found.
> >
> >> LaTeX wrote:
> >>> ! LaTeX Error: Command \gather already defined.
> >>> Or name \end... illegal, see p.192 of the manual.
> >
> >> In my opinion, it is unfortunate that LaTeX is not doing more to help you. In 1992 referring to page 192 of the manual is appropriate. In 2022 (nearly 2023) it is not.
> >
> > I've been able to get a secondhand copy of the 'The Latex Companion', 2nd edition, 2004 version. And page 192 is blank, and is on the left-hand side facing Chapter 4, The Layout of the Page.
> >
> > So what manual is the error report referring to please?
> That would be LaTeX: A Document Preparation System, by Leslie Lamport.
> But I have to agree with Jonathan Fine that refering to a page in that
> manual isn't particulary useful. I have my doubts if even in 1992 it was
> useful.

I recently encountered the same error message as the OP. It was in a rather complicated article manuscript that used the publisher's LaTeX template. Said template loads a lot of packages by default, including lineno and amsmath. I had been using MikTex 2.9, and the document compiled fine. Last week I installed Texlive 2022, since my MikTex was getting rather old and did not seem to have the latexdiff functionality that I needed. Now, compling with TexLive 2022, I get that error message about the gather command being already defined, referencing some lines in amsmath.sty. Since I did not see one in this thread, FWIW I offer the following MWE. Simply switch the order of \usepackage{amsmath} and \usepackage{lineno}, so that latter comes first, and the problem will occur. In the other order, it compiles fine.

\documentclass{article}
\usepackage{lipsum}

\usepackage{lineno}
\usepackage{amsmath}

\begin{document}

\section{Response to reviewer 2 comments}

Reviewer question 1

My response: \lipsum[1]

\end{document}