What causes "No OpenRouter image generation model was set." in Mintplex-Labs/anything-llm?

Set IMAGE_GEN_MODEL_PREF to an image-capable OpenRouter model slug in .env and restart

No OpenRouter image generation model was set.

Error message

No OpenRouter image generation model was set.

What it means

OpenRouterImageGenerator's constructor throws when process.env.IMAGE_GEN_MODEL_PREF is unset or empty. Unlike the API key, this variable is shared across image generation providers, so it must be set even though it is not OpenRouter-specific.

Solutions

Set IMAGE_GEN_MODEL_PREF to an image-capable OpenRouter model slug in .env and restart
Pick the model via the app's image generation settings UI so the variable is persisted
Confirm the variable is non-empty at runtime (console.log(process.env.IMAGE_GEN_MODEL_PREF))
For Docker, pass the variable into the container environment

Example fix

# before (.env)
IMAGE_GEN_OPENROUTER_API_KEY=sk-or-v1-...

# after (.env)
IMAGE_GEN_OPENROUTER_API_KEY=sk-or-v1-...
IMAGE_GEN_MODEL_PREF=google/gemini-2.5-flash-image-preview

Defensive patterns

Strategy: validation

Validate before calling

if (!process.env.IMAGE_GEN_MODEL_PREF) {
  throw new Error('Set IMAGE_GEN_MODEL_PREF to an image-capable model before enabling the engine.');
}

Try / catch

try {
  generator = new OpenRouterImageGenerator();
} catch (err) {
  if (err.message.includes('image generation model')) {
    // prompt the user to pick a model in settings
  }
  throw err;
}

Prevention

Enforce model selection in the settings UI before the engine can be saved as active
Remember IMAGE_GEN_MODEL_PREF is shared across image providers — always re-set it when switching engines
Validate env at boot and report all missing image-gen variables together

When it happens

Trigger: OpenRouter image engine selected but IMAGE_GEN_MODEL_PREF was never set in the environment; the variable was cleared when switching from a different image provider that also uses it.

Common situations: User set the OpenRouter key but never chose a model; .env edited while server running (stale env); deployment pipeline dropping the variable; empty string value after a settings save.

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/eeda78e441b776c3. Report an issue: GitHub.

Appendix: source

Thrown at server/utils/ImageGenerators/openRouter/index.js:13

const { BaseImageGenerator } = require("../base");

class OpenRouterImageGenerator extends BaseImageGenerator {
  _extractImageBuffer(dataUrl) {
    if (!dataUrl) throw new Error("OpenRouter returned no image data.");
    return Buffer.from(dataUrl.split(",").pop(), "base64");
  }

  constructor() {
    if (!process.env.IMAGE_GEN_OPENROUTER_API_KEY)
      throw new Error("No OpenRouter image generation API key was set.");
    if (!process.env.IMAGE_GEN_MODEL_PREF)
      throw new Error("No OpenRouter image generation model was set.");
    const { OpenAI: OpenAIApi } = require("openai");
    super({
      client: new OpenAIApi({
        baseURL: "https://openrouter.ai/api/v1",
        apiKey: process.env.IMAGE_GEN_OPENROUTER_API_KEY,
        defaultHeaders: {
          "HTTP-Referer": "https://anythingllm.com",
          "X-Title": "AnythingLLM",
        },
      }),
      model: process.env.IMAGE_GEN_MODEL_PREF,
      className: "OpenRouterImageGenerator",
    });
  }

  // OpenRouter does not expose /images/generations. Its image models return
  // images through chat completions with the "image" output modality, where the
  // image comes back as a base64 data URL in `message.images`.

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