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

Set TTS_OPEN_AI_KEY=sk-... explicitly in the server environment 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 TTS_OPEN_AI_KEY is unset. This is a separate variable from OPEN_AI_KEY (used by STT) and from the LLM provider keys — AnythingLLM deliberately scopes TTS credentials to TTS_OPEN_AI_*, so having a working chat/STT key does not satisfy this check. The voice defaults to 'alloy' via TTS_OPEN_AI_VOICE_MODEL and the model is hardcoded to tts-1.

Solutions

Set TTS_OPEN_AI_KEY=sk-... explicitly in the server environment and restart.
Confirm you are not relying on OPEN_AI_KEY — the TTS class only reads TTS_OPEN_AI_KEY.
Optionally set TTS_OPEN_AI_VOICE_MODEL (e.g. nova, shimmer) — defaults to alloy if omitted.
Verify the key has access to the tts-1 model on your OpenAI account.

Example fix

# before (.env)
TTS_PROVIDER=openai
OPEN_AI_KEY=sk-abc        # wrong var for TTS
# -> Error: No OpenAI API key was set.

# after (.env)
TTS_PROVIDER=openai
TTS_OPEN_AI_KEY=sk-abc    # correct var
TTS_OPEN_AI_VOICE_MODEL=alloy

Defensive patterns

Strategy: validation

Validate before calling

const canUseOpenAiTTS = () => Boolean(process.env.TTS_OPEN_AI_KEY);

if ((process.env.TTS_PROVIDER || "openai") === "openai" && !canUseOpenAiTTS()) {
  throw new Error("openai TTS requires TTS_OPEN_AI_KEY (OPEN_AI_KEY is NOT used for TTS)");
}

Try / catch

try {
  tts = getTTSProvider();
} catch (e) {
  if (/No OpenAI API key was set/.test(e.message) && (process.env.TTS_PROVIDER || "openai") === "openai")
    return respondConfigError("TTS_OPEN_AI_KEY missing");
  throw e;
}

Prevention

Don't assume key reuse: chat (LLM provider key), STT (OPEN_AI_KEY), and TTS (TTS_OPEN_AI_KEY) are separate variables in this codebase.
Add a deploy-time assertion listing all three OpenAI-related vars and which subsystem each unlocks.
Restart the process after .env changes; Node reads env once at boot.

When it happens

Trigger: TTS_PROVIDER=openai (the default) and any speech-generation request while TTS_OPEN_AI_KEY is missing from the server environment.

Common situations: User sets OPEN_AI_KEY for chat, assumes TTS inherits it, and never sets TTS_OPEN_AI_KEY; .env updated but container not restarted; key placed under the generic-openai variables (TTS_OPEN_AI_COMPATIBLE_KEY) by mistake.

Understand the failure class

Background: "environment variable is not set" and "Missing keys in environment" errors: what missing required env var messages mean and how to fix them — this error's family across 28 libraries.

Related errors

AI-assisted analysis of Mintplex-Labs/anything-llm@3aec848f28 (2026-08-18). Data as JSON: /api/errors/1b170adb51bba041. Report an issue: GitHub.

Appendix: 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);
    }

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