Okay, I think I'm getting close, but I'm not quite there yet. The pagecolumns source code is found in page-pcl.mkiv (source.contextgarden.net/tex/context/base/mkiv/page-pcl.mkiv), and in that code, the \page_col_stop_yes macro seems to have something to do with the issue:

```
\unexpanded\def\page_col_stop_yes
  {\column % \page_otr_eject_page
   \page
   \endgroup
 % \setupoutputroutine[\s!singlecolumn]%
   \page_otr_command_set_vsize
   \page_otr_command_set_hsize
   \page
   \endgroup}
```

If I redefine this macro in my MWE as follows, I can remove the extra page that is added when the last page ends with text in the last column:

```

\unprotect

\def\page_col_stop_yes

{\column %\page_otr_eject_page

%\page

\endgroup

% \setupoutputroutine[\s!singlecolumn]%

\page_otr_command_set_vsize

\page_otr_command_set_hsize

%\page

\endgroup}

\protect

```

Commenting out the \page calls does the trick in this case, but now, if the last page ends with its text in a column before the last one, then the last page is not typeset at all, and a blank page takes its place.

On Sun, May 10, 2020 at 8:34 PM Thangalin <thangalin@gmail.com> wrote:
Bump.

See also: https://tex.stackexchange.com/q/542993/2148

On Mon, May 4, 2020 at 11:46 AM Joey McCollum
<jmccollum20140511@gmail.com> wrote:
>
> After continuing to look into this a bit, I noticed that a similar issue involving the insertion of a blank page after a columnset environment has been discussed on the mailing list in the thread "Blank page inserted when text reaches column's end" (dated 08 Dec 2019). In that thread, a proposed solution was to redefine the \page_grd_stop macro found in page-cst.mkiv as follows:
>
> ```
> \unprotect
> \def\page_grd_stop{%
>   \endgraf % needed, else wrong vsize in one par case
>   \vfill % otherwise weird \placenotes[endnotes]
>   \page_grd_command_set_vsize % needed
>   \penalty\c_page_otr_eject_penalty
>   %\page_grd_command_flush_page
>   \page_otr_fill_and_eject_page
>   \page_grd_command_set_vsize % why here
>   \egroup
>   \page_otr_command_set_vsize
>   \page_otr_command_set_hsize
> }
> \protect
> ```
>
> Unfortunately, this approach was found to have potential issues in that thread, and it does not fix the problem with pagecolumns in my MWE. Are pagecolumns commands aliased to pagegrid commands like columnset commands are, or are they defined somewhere else? I checked page-col.mkiv, but it seems to be too short to be the file that defines pagecolumns behavior.
>
> Joey
>
> On Sat, May 2, 2020 at 11:46 AM Joey McCollum <jmccollum20140511@gmail.com> wrote:
>>
>> I recently found the pagecolumns manual (http://www.pragma-ade.com/general/manuals/pagecolumns.pdf), and in several of the examples (including those for side floats and footnotes), the addition of a blank page after the end of the pagecolumns environment also seems to occur. So when the manual says, "We always start at a new page and end on a new one," does it mean that this is a feature of pagecolumns? And if so, is there any way to disable it? I have no problem with a page break after the end of the pagecolumns environment, but an empty page added after the break seems unnecessary. I checked for a wiki page on the \definepagecolumns command to get more information on its accepted inputs, but there doesn't appear to be a page for this command.
>>
>> Joey
>>
>> On Tue, Apr 28, 2020 at 1:40 PM Joey McCollum <jmccollum20140511@gmail.com> wrote:
>>>
>>> I am typesetting a document using pagecolumns to ensure that my footnotes are set ragged-bottom in columns. I have observed some unexpected behavior whenever the last column on a page is left incomplete: a blank page is added at the end of the document. A minimal working example follows:
>>>
>>> ```
>>>
>>> \starttext
>>>
>>> \startpagecolumns[n=2]
>>>
>>> \dorecurse{3}{\par\input zapf}
>>>
>>> \stoppagecolumns
>>>
>>> \stoptext
>>>
>>> ```
>>>
>>> I typeset this using ConTeXt version 2020.03.10, as released with TeXLive 2020. Notably, if \dorecurse{3} is changed to \dorecurse{2} or \dorecurse{6} (so that the text ends in the first column of a page), then there is no problem. I have tried to fix this by specifying page=no in the \startpagecolumns arguments, but it did not change anything. Is there something else I am missing?
>>>
>>> Thank you,
>>>
>>> Joey
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
> archive  : https://bitbucket.org/phg/context-mirror/commits/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________