# Why do Vosk captions stop when several people speak in Jitsi?

> Older Jigasi builds can corrupt valid Vosk replies when participant sessions parse messages concurrently. Jigasi PR #647 fixes the shared parser, and Docker stable-11248 includes the fixed package, 1.1-415-g2750d54-1. Upgrade the running transcriber, then test captions from several speakers; restarting an older build does not install the fix. [S1][S2][S3][S9]

Source: https://jitsi.help/troubleshooting/vosk-captions-drop-several-speakers/
Updated: October 12, 2026
Publisher: Jitsi Help (https://jitsi.help/)

## Symptoms

Some speakers lose captions during a meeting with several speakers. The report was reproduced on Docker `stable-9955`, using Jigasi `1.1-369-gb80d3df`. These are the exact parsing lines from PR #647, including the valid JSON reply: [S1]

```text
SEVERE: VoskWebsocketStreamingSession.onMessage: Error parsing message: {
  "partial" : "the out for the ancient"
}
Unexpected character (") at position 29.
```

The report also includes these streaming-error fragments: [S1]

```text
SEVERE: VoskWebsocketStreamingSession.onError: Error while streaming audio data
        to transcription service
java.util.NoSuchElementException
  at VoskTranscriptionService.onMessageInternal(VoskTranscriptionService.java:286)
```

Your timestamp, text and source line number can differ. The useful clue is a parsing failure on a valid Vosk response while multiple participant sessions are active. Not every meeting with several people necessarily reproduces the race. [S1][S2]

## Cause

Older `VoskTranscriptionService` code used one `JSONParser` for multiple participant sessions. Jetty can deliver their WebSocket callbacks concurrently. Each parse changes the parser's internal state, so another callback can overwrite it mid-parse. Valid JSON can then fail, or results can contain another participant's text, as the contributor's stress test reported. [S1][S2]

The merged fix uses `ThreadLocal<JSONParser>` and calls `jsonParser.get().parse(msg)`. This gives each callback thread its own parser. It is a Jigasi code fix, with no new Vosk model or configuration setting required. [S2]

PR #647 merged on September 11, 2026, as commit `2750d54`. The official September 14 `stable-11248` Jigasi image build installed `1.1-415-g2750d54-1` for both `linux/amd64` and `linux/arm64`. The previous stable Docker release was `stable-11146-2`, published August 17, before the fix. `stable-11248` is therefore the first stable Docker release containing it, and remained the latest when checked on October 12, 2026. [S1][S3][S4]

The Jitsi stable APT repository also offers `1.1-415-g2750d54-1`. The web changelog records Jitsi Meet `2.0.11248`, but does not list this Jigasi fix. The package index and image build logs establish the transcriber version directly. [S3][S5][S6]

## Fix

1. **Docker, existing Vosk transcription installations: check the running service.** Run this from your Docker deployment directory. The stock service is `transcriber`, using the Jigasi image. Include every overlay you normally deploy in the helper. If your custom setup runs transcription in a service named `jigasi`, use that name in the service-specific commands. [S7][S8]

   ```sh
   dc() {
       docker compose -f docker-compose.yml -f transcriber.yml "$@"
   }
   dc images transcriber
   dc exec -T transcriber dpkg-query -W -f='${Version}\n' jigasi
   dc logs --tail=200 transcriber
   ```

   Image inspection, execution and log options are documented by Docker; the package query reads the installed version inside the running container. Save the error context before replacing it. [S10][S11]

2. **Docker, upgrade to `stable-11248`: update the release files and images together.** Follow the handbook's updating section to replace the Compose files with those from the release. Keep your existing `.env`, credentials and configuration. When upgrading from before `stable-11146`, follow its rootless directory migration too, including writable storage directories for UID 1000. [S7]

   Set this existing image selector in `.env`: [S8]

   ```ini
   JITSI_IMAGE_VERSION=stable-11248
   ```

   Then run the helper from step 1 during a maintenance window: [S9][S10]

   ```sh
   dc config --images
   dc pull
   dc up -d
   dc images
   dc exec -T transcriber dpkg-query -W -f='${Version}\n' jigasi
   ```

   Check that every Jitsi component uses `stable-11248`. Your separate Vosk image has its own version. `pull` downloads images; `up -d` recreates services whose images or configuration changed. A restart of an old container alone does not replace its image. [S8][S9][S10]

3. **Debian/Ubuntu packages, Jigasi before the fix: upgrade Jigasi itself.** These commands assume the official Jitsi stable APT repository is already configured. Check its candidate before installing. At the research date, the confirmed fixed candidate was `1.1-415-g2750d54-1`. [S5][S12][S13]

   ```sh
   dpkg-query -W -f='${Version}\n' jigasi
   sudo apt-get update
   apt-cache policy jigasi
   sudo apt-get install --only-upgrade jigasi
   sudo systemctl restart jigasi
   dpkg-query -W -f='${Version}\n' jigasi
   systemctl is-active jigasi
   ```

   Use your normal package configuration review during the upgrade. The service is named `jigasi`; restarting it ensures the process loads the updated code. An OS release name alone does not establish which Jigasi build is running. [S11][S13][S14]

No confirmed configuration-only workaround was supplied in PR #647. Treat reducing simultaneous speakers or restarting old Jigasi as unverified mitigation, not a substitute for upgrading. Use the existing [Vosk setup guide](/guides/jitsi-transcription-vosk/) for backend configuration. [S1][S2]

## Verify

For Docker after step 2, the installed-package command must print exactly this version for the build verified here. The same output applies to packages after step 3: [S3][S5][S11]

```text
1.1-415-g2750d54-1
```

On package installations, `systemctl is-active jigasi` should print `active`. That confirms service state, not successful captions. [S14]

For both install types, run a fresh test meeting on `meet.example.com`. Have several participants speak, including overlapping speech, and confirm captions continue for each person. Check that the reproduced test produces no new parsing or streaming errors shown above. This is a proposed functional test, not a load test performed by jitsi.help. The upstream contributor's parser stress test was clean after the change. [S1][S2]

## If it still fails

**Docker `stable-11248`:** follow the transcriber log while repeating the test: [S7][S10]

```sh
dc logs --since=10m --follow transcriber
```

**Debian/Ubuntu, fixed package:** the upstream unit redirects application output to `/var/log/jitsi/jigasi.log`. Read that file for parsing errors; the journal is useful for service startup failures. Custom units can change logging, so inspect the actual unit if this file stays empty. [S15][S16][S17]

```sh
sudo tail -n 200 /var/log/jitsi/jigasi.log
systemctl cat jigasi
sudo journalctl -u jigasi -n 100 --no-pager
```

Recheck every transcriber instance's installed package. For a custom build, verify it contains commit `2750d54`; a reassuring image name alone is insufficient evidence. In the released Vosk class, `Error to send websocket request for participant ` and `Error to finalize websocket connection for participant ` are distinct send/finalization log prefixes. Investigate those separately rather than treating every WebSocket error as this parser race. [S2][S11]

Use [transcription not working](/troubleshooting/jitsi-transcription-not-working/) for setup failures. If you need help gathering evidence across several instances, our [transcription service](/services/jitsi-transcription/) covers that investigation.

## FAQ

### Does stable-11248 include the Vosk parser fix?

Yes. Its official Jigasi image build installed `1.1-415-g2750d54-1` on both supported build architectures. That package's commit is the merged PR #647 fix. [S1][S3]

### Does Unexpected character mean Vosk sent invalid JSON?

Not necessarily. The reported reply was valid JSON; concurrent callbacks corrupted the shared parser's state. Genuine invalid responses still need investigation after installing the fix. [S1][S2]

### Will restarting Jigasi solve it?

A restart does not add the missing code to an older container or package. Install the fixed build and recreate the container or restart the upgraded package service. [S2][S9][S14]

### Is this the same as Jigasi running out of memory?

This page covers the parser race fixed by PR #647. The [Jigasi memory troubleshooting page](/troubleshooting/jigasi-out-of-memory/) covers a separate investigation; this parser change does not establish that all resource or connection-lifecycle problems are fixed. [S2]

## Sources

[S1] [Jigasi PR #647](https://github.com/jitsi/jigasi/pull/647), merged 2026-09-11, community production report and maintainer-approved repository fix.

[S2] [Released VoskTranscriptionService.java](https://github.com/jitsi/jigasi/blob/2750d5448271a7a421cb28a914970a4383127380/src/main/java/org/jitsi/jigasi/transcription/VoskTranscriptionService.java), 2026-09-11, source code.

[S3] [stable-11248 Jigasi image build](https://github.com/jitsi/docker-jitsi-meet/actions/runs/34847486800/job/103989057148), 2026-09-14, official repository build log; package installation verified through GitHub's authenticated log download.

[S4] [Docker releases](https://github.com/jitsi/docker-jitsi-meet/releases), checked 2026-10-12, release notes.

[S5] [Jitsi stable package index](https://download.jitsi.org/stable/Packages), checked 2026-10-12, official repository metadata.

[S6] [Jitsi web changelog](https://github.com/jitsi/jitsi-meet-release-notes/blob/master/CHANGELOG-WEB.md), 2026-09-14 release, release notes.

[S7] [Docker handbook](https://jitsi.github.io/handbook/docs/devops-guide/devops-guide-docker/), checked 2026-10-12, official doc.

[S8] [stable-11248 transcriber.yml](https://github.com/jitsi/docker-jitsi-meet/blob/stable-11248/transcriber.yml), 2026-09-14 release, source code.

[S9] Docker [pull](https://docs.docker.com/reference/cli/docker/compose/pull/) and [up](https://docs.docker.com/reference/cli/docker/compose/up/), checked 2026-10-12, official docs.

[S10] Docker [images](https://docs.docker.com/reference/cli/docker/compose/images/), [config](https://docs.docker.com/reference/cli/docker/compose/config/), [exec](https://docs.docker.com/reference/cli/docker/compose/exec/) and [logs](https://docs.docker.com/reference/cli/docker/compose/logs/), checked 2026-10-12, official docs.

[S11] [dpkg-query](https://manpages.debian.org/bookworm/dpkg/dpkg-query.1.en.html), checked 2026-10-12, official Debian manual.

[S12] [Debian/Ubuntu handbook](https://jitsi.github.io/handbook/docs/devops-guide/devops-guide-quickstart/), checked 2026-10-12, official doc.

[S13] [apt-get](https://manpages.debian.org/bookworm/apt/apt-get.8.en.html) and [apt-cache](https://manpages.debian.org/bookworm/apt/apt-cache.8.en.html), checked 2026-10-12, official Debian manuals.

[S14] [systemctl](https://manpages.debian.org/bookworm/systemd/systemctl.1.en.html), checked 2026-10-12, official Debian manual.

[S15] [Jigasi package service unit](https://github.com/jitsi/jigasi/blob/2750d5448271a7a421cb28a914970a4383127380/debian/jigasi.service), 2026-09-11, source code.

[S16] [tail](https://manpages.debian.org/bookworm/coreutils/tail.1.en.html), checked 2026-10-12, official Debian manual.

[S17] [journalctl](https://manpages.debian.org/bookworm/systemd/journalctl.1.en.html), checked 2026-10-12, official Debian manual.

## Open questions

We did not reproduce the concurrency failure or run a sustained multi-speaker test on a real server. PR #647 does not establish a failure probability or participant threshold. Independently built images need their own package/code verification. No reliable pre-upgrade workaround was confirmed. [S1][S2]

---

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