Mintplex-Labs/anything-llm · error

Fallback provider is required.

Error message

Fallback provider is required.

What it means

Validation error from ModelRouter.update relayed by PUT /model-routers/:id: the payload omitted or blanked the fallback provider field, which is required so the router always has a provider to fall back to.

Source

Thrown at server/endpoints/modelRouter.js:82

        if (error) return response.status(400).json({ router, error });
        await Telemetry.sendTelemetry("model_router_created");
        return response.status(200).json({ router });
      } catch (e) {
        console.error(e);
        response.sendStatus(500);
      }
    }
  );

  app.put(
    "/model-routers/:id",
    [validatedRequest, flexUserRoleValid([ROLES.admin])],
    async (request, response) => {
      try {
        const { id } = request.params;
        const data = reqBody(request);
        const { router, error } = await ModelRouter.update(Number(id), data);
        if (error) return response.status(400).json({ router, error });
        ModelRouterService.invalidateRouter(Number(id));
        return response.status(200).json({ router });
      } catch (e) {
        console.error(e);
        response.sendStatus(500);
      }
    }
  );

  app.delete(
    "/model-routers/:id",
    [validatedRequest, flexUserRoleValid([ROLES.admin])],
    async (request, response) => {
      try {
        const { id } = request.params;
        const success = await ModelRouter.delete(Number(id));
        if (!success)
          return response

View on GitHub (pinned to 3aec848f28)

Solutions

1. Include the fallback provider field in the update.
2. Use a supported provider identifier.

When it happens

Trigger: Thrown at server/endpoints/modelRouter.js:82 when the library encounters an invalid state.

Common situations: Router update missing the fallback provider.

AI-assisted analysis of Mintplex-Labs/anything-llm@3aec848f28 (2026-08-18). Data as JSON: /api/errors/bfc794342e4c6f67. Report an issue: GitHub.