What causes "MOSS-TTS (CrispASR) — the crispasr server crashed during synthesis." in SubtitleEdit/subtitleedit?

Inspect the appended `Server log:` tail — the backend crash reason is logged before exit.

SubtitleEdit/subtitleedit · error · InvalidOperationException

MOSS-TTS (CrispASR) — the crispasr server crashed during syn

Error message

MOSS-TTS (CrispASR) — the crispasr server crashed during synthesis.

What it means

InvalidOperationException from the HttpRequestException catch in MossTtsCrispAsr.Speak when the POST to `/v1/audio/speech` fails AND the server process has exited (`died == true`). The MOSS-TTS crispasr server crashed mid-synthesis; StopServerInternal is called, the inner HttpRequestException is chained, and the server log + launch command are appended so the next call starts a fresh server.

Source

Thrown at src/ui/Features/Video/TextToSpeech/Engines/MossTtsCrispAsr.cs:476

            response = await HttpClient.PostAsync($"{ServerBaseUrl}/v1/audio/speech", content, cancellationToken);
        }
        catch (HttpRequestException ex)
        {
            var serverLog = SnapshotServerLog();
            var launchCommand = _serverLaunchCommand;
            var died = _serverProcess?.HasExited == true;
            if (died)
            {
                StopServerInternal();
            }

            var failMsg = $"MOSS-TTS (CrispASR) request failed — Voice: {mossVoice}, Text: {text}, "
                + $"RequestJson: {body}, ServerExited: {died}, ServerLog: {serverLog}"
                + LaunchCmdSuffix(launchCommand);
            Se.LogError(ex, failMsg);
            Se.WriteToolsLog(failMsg);

            throw new InvalidOperationException(
                (died
                    ? "MOSS-TTS (CrispASR) — the crispasr server crashed during synthesis."
                    : "MOSS-TTS (CrispASR) request failed — the connection to the crispasr server was dropped.")
                + (string.IsNullOrEmpty(serverLog) ? string.Empty : $"{Environment.NewLine}Server log:{Environment.NewLine}{serverLog}")
                + LaunchCmdSuffix(launchCommand),
                ex);
        }

        using (response)
        {
            if (!response.IsSuccessStatusCode)
            {
                var errorBody = await SafeReadErrorAsync(response, cancellationToken);
                var serverLog = SnapshotServerLog();
                var launchCommand = _serverLaunchCommand;
                var errMsg = $"MOSS-TTS (CrispASR) server error {(int)response.StatusCode} {response.StatusCode} — "
                    + $"Voice: {mossVoice}, Text: {text}, RequestJson: {body}, "
                    + $"ResponseBody: {errorBody}, ServerLog: {serverLog}"

View on GitHub (pinned to 17a9f07487)

Solutions

Inspect the appended `Server log:` tail — the backend crash reason is logged before exit.
Retry once; EnsureServerRunningAsync starts a fresh server. Repeated death on the same input points to the reference WAV or model.
Re-encode the reference WAV to mono PCM at the expected sample rate.
Free VRAM/RAM at failure time; close other GPU workloads.
Chunk very long input text and retry per chunk.

Defensive patterns

Strategy: retry

Validate before calling

// Before batch synth, confirm server alive and reference WAV valid
if (engine.IsServerDown() || !File.Exists(mossVoice.FilePath)) { WarnUser(...); return; }

Try / catch

try { await mossEngine.Speak(...); }
catch (InvalidOperationException ex) when (ex.Message.Contains("server crashed during synthesis"))
{
    // Server auto-stopped; next call starts fresh. Retry once.
    await mossEngine.Speak(...);
}

Prevention

Pre-validate the reference WAV format (mono PCM) to avoid mid-synth crashes.
Monitor VRAM and skip synth while another GPU job runs.
Serialize Speak calls per server instance.
Log the inner HttpRequestException to correlate with backend traces.

When it happens

Trigger: Reference WAV malformed so the moss backend segfaults during cloning; OOM/GPU fault killing the server mid-inference; corrupt model GGUF aborting on first synth; CUDA driver crash during generation.

Common situations: Reference WAV wrong sample rate/channel layout; VRAM exhausted by another process mid-render; truncated model download; backend bug on specific input.

Related errors

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/3455c44ac87c3b50. Report an issue: GitHub.