vercel/ai · error · UnsupportedFunctionalityError

AI_UnsupportedFunctionalityError

AI_UnsupportedFunctionalityError

Error message

'non-streaming transcription with ${this.modelId}' functionality not supported.

What it means

Error "'non-streaming transcription with ${this.modelId}' functionality not supported." thrown in vercel/ai.

Source

Thrown at packages/cartesia/src/cartesia-transcription-model.ts:140

      }
      if (cartesiaOptions.timestampGranularities != null) {
        for (const granularity of cartesiaOptions.timestampGranularities) {
          formData.append('timestamp_granularities[]', granularity);
        }
      }
    }

    return {
      formData,
      warnings,
    };
  }

  async doGenerate(
    options: Parameters<TranscriptionModelV4['doGenerate']>[0],
  ): Promise<Awaited<ReturnType<TranscriptionModelV4['doGenerate']>>> {
    if (isStreamingTranscriptionModelId(this.modelId)) {
      throw new UnsupportedFunctionalityError({
        functionality: `non-streaming transcription with ${this.modelId}`,
      });
    }

    const currentDate = this.config._internal?.currentDate?.() ?? new Date();
    const { formData, warnings } = await this.getArgs(options);

    const {
      value: response,
      responseHeaders,
      rawValue: rawResponse,
    } = await postFormDataToApi({
      url: this.config.url({
        path: '/stt',
        modelId: this.modelId,
      }),
      headers: combineHeaders(this.config.headers?.(), options.headers),
      formData,

View on GitHub (pinned to 69428b1f8b)

When it happens

Trigger: Thrown at packages/cartesia/src/cartesia-transcription-model.ts:140 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/4dea57a40ac73cde. Report an issue: GitHub.