Posit Connect - Unable to read quarto extension

[DOH-FAA3303]

Description

I am using Posit Workbench and am trying to publish a quarto document to Posit Connect. The document is using a custom extension in the _extensions folder, and renders just fine locally/in Workbench, but fails every time when publishing to Connect because Connect cannot find that _extensions folder.

I don't think this is the right place to discuss it, but I cannot find a similar forum for rsconnect. I made a reproducible repo here:

https://github.com/DOH-FAA3303/quarto-publish-error

These are the steps I've taken:

rsconnect write-manifest quarto --overwrite --package-installer UV template.qmd

rsconnect deploy manifest manifest.json 

Then it fails with

2026/08/13 16:59:16.753698480 [connect-quarto] Running 'quarto render'
2026/08/13 16:59:17.806101000 ERROR: Unable to read the extension 'two_pager'.
2026/08/13 16:59:17.806117801 Please ensure that you provided the correct id and that the extension is installed.

I have tried to run Posit Publisher in Positron and checking the box to include the _extensions folder in the toml, but same error.

If this is not the right forum, where can I request for help?

[mcanouil]

At first glance, I would say you are publishing a single document instead of a project by specifying the document, thus perhaps why everything else is lost.
Look at the publish manifest what it holds.

[DOH-FAA3303]

looks like we commented at the same time. I found the solution with the answer below. I did need to specify all the files in the manifest.

I got tons of other errors too, but worked through them. rsconnect and publisher seem a bit unstable, or maybe my environment is unstable

[DOH-FAA3303]

Resolved..

You need to write all files to the manifest like:

rsconnect write-manifest quarto \
  --overwrite \
  template.qmd \
  _extensions/my-extension/_extension.yml \
  _extensions/my-extension/template.html \
  _extensions/my-extension/styles.css \
  _extensions/my-extension/template.tex

note: UV would not work no matter what I tried, so I had to export the uv.lock to requirements.txt:

uv export \
  --locked \
  --format requirements.txt \
  --no-hashes \
  --output-file requirements.txt

then run

rsconnect deploy manifest manifest.json 

That failed for me with this error:

[ERROR]: 'utf-8' codec can't decode byte 0x80 in positon 10: invalid start byte

I fixed it with --no-verify

rsconnect deploy manifest manifest.json --no-verify

tl;dr - getting quarto to publish in posit takes some effort :(

[mcanouil]

I'm not sure rsconnect has all the tooling, but you should be able to publish a "default" project by targeting _quarto.yml.
It should populate the manifest.

Did you try quarto publish?

[DOH-FAA3303]

quarto publish works but doesn't give me the ability to automatically render on a schedule in my private Posit Connect instance, whereas rsconnect does. (unless I'm mistaken)

This is what I get when I deploy from rsconnect:

vs quarto publish:

edit - as confirmed here https://quarto.org/docs/publishing/rstudio-connect.html