What causes "No OpenAI API key was set." in Mintplex-Labs/anything-llm?

Add TTS_OPEN_AI_KEY= to .env and restart.

Mintplex-Labs/anything-llm · error · Error

No OpenAI API key was set.

Error message

No OpenAI API key was set.

What it means

Thrown by the OpenAiTTS constructor when process.env.TTS_OPEN_AI_KEY is falsy. Note this uses a dedicated TTS_OPEN_AI_KEY, distinct from the main OPEN_AI_KEY used by STT. The class builds an OpenAI client for the tts-1 audio.speech API. Without the key the client cannot authenticate.

Source

Thrown at server/utils/TextToSpeech/openAi/index.js:4

class OpenAiTTS {
  constructor() {
    if (!process.env.TTS_OPEN_AI_KEY)
      throw new Error("No OpenAI API key was set.");
    const { OpenAI: OpenAIApi } = require("openai");
    this.openai = new OpenAIApi({
      apiKey: process.env.TTS_OPEN_AI_KEY,
    });
    this.voice = process.env.TTS_OPEN_AI_VOICE_MODEL ?? "alloy";
  }

  async ttsBuffer(textInput) {
    try {
      const result = await this.openai.audio.speech.create({
        model: "tts-1",
        voice: this.voice,
        input: textInput,
      });
      return Buffer.from(await result.arrayBuffer());
    } catch (e) {
      console.error(e);
    }

View on GitHub (pinned to 526360e320)

Solutions

Add TTS_OPEN_AI_KEY=<sk-...> to .env and restart.
Confirm the exact name is TTS_OPEN_AI_KEY, not OPEN_AI_KEY.
Optionally set TTS_OPEN_AI_VOICE_MODEL (defaults to 'alloy').
In Docker, pass the variable to the container.

Example fix

# before
# TTS_PROVIDER unset → defaults to openai
# TTS_OPEN_AI_KEY missing

# after
TTS_PROVIDER=openai
TTS_OPEN_AI_KEY=sk-xxxxxxxx

Defensive patterns

Strategy: validation

Validate before calling

if (
  (process.env.TTS_PROVIDER || "openai") === "openai" &&
  !process.env.TTS_OPEN_AI_KEY
) {
  throw new Error(
    "TTS provider is 'openai' but TTS_OPEN_AI_KEY is not set (this is separate from OPEN_AI_KEY)."
  );
}

Try / catch

try {
  return new OpenAiTTS();
} catch (e) {
  if (/No OpenAI API key/i.test(e.message)) {
    logger.error("Set TTS_OPEN_AI_KEY (dedicated TTS key) in .env, then restart.");
  }
  throw e;
}

Prevention

Remember TTS uses TTS_OPEN_AI_KEY, NOT the shared OPEN_AI_KEY — they are distinct.
Since 'openai' is the default TTS provider, this key is effectively required unless you switch providers.
Restart after editing .env.

When it happens

Trigger: TTS_PROVIDER=openai (the default) is active but TTS_OPEN_AI_KEY is missing/empty; the key was added but the process not restarted; confusion between OPEN_AI_KEY and TTS_OPEN_AI_KEY.

Common situations: Fresh install relying on default TTS provider without setting a dedicated TTS key; rotated key not updated; Docker env not passed through; assuming OPEN_AI_KEY covers TTS (it does not — TTS needs TTS_OPEN_AI_KEY).

Related errors

AI-assisted analysis of Mintplex-Labs/anything-llm@526360e320 (2026-08-13). Data as JSON: /api/errors/1b170adb51bba041. Report an issue: GitHub.