Quarto book preview: "WARN: connection closed before message completed" any clue?

[simosacchi]

Description

Dear all,

I am experiencing a frustrating situation. I am on MacOS Sonoma 14.4.1, Quarto 1.5.45, and the same behaviour happens with Chrome, Sarafi and Firefox.
This is the issue. After a while (and I cannot reproduce exactly when), when I launch "quarto preview" (options do not change the behaviour), I start getting a "WARN: connection closed before message completed" when navigating the website, and I am stuck on the original page. The behaviour seems to hit after several pages are added to the YAML file. All pages are just Markdown (no code).

I have tried building the site from scratch several times, the last one keeping the preview running with the --watch-inputs. It worked properly until I killed the process. Running the process again brought back the warning and got me stuck again.

Even more strangely, repeatedly hitting the link gets me to the desired page at some point. Moreover, if I open different pages of the website (e.g. http://localhost:3604/index.html and http://localhost:3604/preface.html) on different tabs, once I reach three open pages, I can see in the STDOUT of the terminal that they reload in a cycle without stopping.

I am completely puzzled.

Thank you for any suggestions.

best,
Simone

[simosacchi]

I have just discovered that "quarto preview --render html" creates yet another scenario:

• if no changes are applied, the preview works properly
• a change to the YAML file is enough to bring the WARN back.

[mcanouil]

Without a fully reproducible example/workflow, hard to guess or figure out the issue unfortunately.

[simosacchi]

@mcanouil I opened the GitHub repo for the project and prepared a GitHub Pages version as well, so the full source is available:

• repo: https://github.com/EUI-Library/research-data-guide
• page: https://eui-library.github.io/research-data-guide/

In terms of workflow, I am running Quarto 1.5.43 within VScode 1.90.0 on MacOS 14.4.1

Please note that the behaviour started happening more or less a week ago. I have only used Quarto for a few weeks now and it used to work properly. I am not aware on any change and/or update in the system in the meanwhile.

Reproducing the issue

Here is how (at least) I ended up with the WARN issue:

• checkout the repo
• run quarto preview
  • server goes up as it should and page is served in the browser
  • if you try to navigate to a different page a "WARN: connection closed before message completed" message is sent to STDOUT and the original page is reloaded twice (at least according to STDOUT)
  • if you open a page in a different browser tab, the page opens, but it triggers a reloading loop on both open tabs (according to STDOUT and the browser icon)
  • loop stops as you close one of the two tabs

The only way I found to avoid the behaviour above is to:

• checkout the repo
• launch preview with render option quarto preview --render html
• navigation works perfectly, no issue
• now, edit a page (e.g. dmp.qmd)
  • page is reloaded (according to watch input), and edit is rendered
  • if you try to navigate to a different page, a "WARN: connection closed before message completed" message is sent to STDOUT and the original page is reloaded twice (at least according to STDOUT)

I hope the above can be considered a reproducible example. At least, that is the behaviour on my machine (I have the same behaviour with Chrome, Safari and Firefox).

Thank you for any help!

[mcanouil]

Thanks for the details. We'll get back to you.

Please note that the behaviour started happening more or less a week ago.

Seems to coincide with the monthly VSCode update (first Thursday of the month).

[simosacchi]

On the VSCode update timing: even running commands in the terminal (not inside VSCode) the issue persists.

Looking forward to hearing back. Thanks!

[gordonwoodhull]

FWIW I see slightly different, but also bad, behavior on cloning your repo and previewing (via the command line).

On my machine the navigation does go through, but the page reloads multiple times, and the console shows both the previous page and the new page load many times.

Behavior is consistent with rendering somehow touching a source file, causing a re-render. Presumably the warning happens when the re-render interrupts an HTTP transfer, but the reload does not always cause the warning.

Looking at the timestamps in the directory, I see the .quarto directory getting updated every reload, but I don't see changes to other files.

[simosacchi]

thanks @gordonwoodhull . I feared that there may be differences when reproducing, as the behaviour I am experiencing seems so odd.

[skwde]

The same also happens to me for some time now (~O(weeks)) when previewing revealjs slides.

Even though in terminal it looks normal and reloads, the VSCode preview (Simple browser) is not updated.
When I manually click the reload button in it, the warning is displayed multiple times.
The number of the same warning though varies.

Note, there is a possibly related (closed by @cscheid on Nov 2022) issue: #3045

[cscheid]

I can't think of anything, unfortunately.

[gordonwoodhull]

It’s easy to repro using the original @simosacchi repository, which is fairly straightforward but has a lot of content.

[andrew-1234]

Before we have a small reprex to be able to localize the problem, it'll be hard for us to do much about it :(

reprex was provided just one comment above what you replied to

[cscheid]

@andrew-1234 "small reprex" with emphasis on small, FYI.

[winniehell]

size of the document may be the key here. preview worked for me without problems but as my document grew I'm now getting that error message on almost every run. involved software versions have not changed in the meantime.

so providing a small reproduction example may not be possible.

[benkeks]

The whole navigation of previews seems to be fundamentally broken if book chapters have long render times. (This issue has also annoyed me a lot over the last months of writing my thesis...)

The problem seems to be connected to the window.location.reload() happening in

quarto-cli/src/webui/quarto-preview/src/server/navigation.ts

Lines 26 to 30 in a496e0e

	if (target && (target !== normalizeTarget(window.location.pathname))) {
	window.location.replace(target);
	} else {
	window.location.reload();
	}

If I change the else case to only fire if a target has been set, the previewer can handle navigation on documents with long render times.

if (target && (target !== normalizeTarget(window.location.pathname))) {
  window.location.replace(target);
} else if (target) {
  window.location.reload();
}

However, I have a really hard time to understand how the previewer messages are supposed to interact and what role the reload should play in there if target is the empty string. So I can't propose a PR. (Removing the window reload creates another glitch where the “Render” dialog does not go away after the rendering, if one accidentally starts multiple renders, e.g. due to mousehover Tippy.js popups. At least for me, the latter glitch is far less annoying than perpetually using touch _quarto.yml...)

Related to issue #11475.

[joshbrake]

Just wanted to chime in to say that I too am experiencing this issue and agree with @winniehell that the size of the document seems to be a key variable. In my experience, the preview works fine until the project grows to a certain size after which this error happens constantly and makes the preview server functionality very frustrating to attempt to use.

I am suspicious that @benkeks is on the right track with long render times being the culprit.