Fallback Configuration

Overview

Model steps support an optional fallback that automatically retries with an alternative model if the primary model fails. This keeps your workflow humming along even during temporary outages or rate limits.

How It Works

Execute the primary model with configured parameters
If primary fails, automatically execute the fallback model
If both fail, mark the step as failed

Configuration

Add a fallback object to any model step:

{
  "step_id": "generate_image",
  "type": "model",
  "model": "flux-dev",
  "params": {
    "prompt": "{{inputs.prompt}}",
    "num_images": 1
  },
  "fallback": {
    "enabled": true,
    "model": "flux-1-1-pro",
    "params": {
      "prompt": "{{inputs.prompt}}",
      "guidance_scale": 7.5
    }
  }
}

Fallback Properties

Property	Type	Default	Description
`enabled`	boolean	`true`	Enable/disable fallback
`model`	string	`-`	Alternative model slug
`version`	string	Primary version	Fallback model version
`params`	object	`-`	Parameters for the fallback model (supports template variables)

Detecting Fallback Usage

When a fallback is used, the step metadata includes:

{
  "step_id": "generate_image",
  "status": "completed",
  "output": "https://storage.googleapis.com/uploads/image.png",
  "metadata": {
    "model": "flux-1-1-pro",
    "fallback_used": true,
    "primary_error": "Primary model flux-dev failed: rate limit exceeded"
  }
}

Field	Description
`fallback_used`	`true` when step completed using fallback
`primary_error`	Why the primary model failed

Best Practices

Choose fallback models that produce compatible output formats
Use fallback for critical production workflows
Monitor fallback_used in execution results to identify recurring primary failures
Consider cost differences between primary and fallback models

Last modified on March 6, 2026

Parameter References

List Categories

Overview

Concepts

API Reference

OpenAPI Reference

Webhooks

Examples

Fallback Configuration

Overview

How It Works

Configuration

Fallback Properties

Detecting Fallback Usage

Best Practices

​Overview

​How It Works

​Configuration

​Fallback Properties

​Detecting Fallback Usage

​Best Practices

Overview

How It Works

Configuration

Fallback Properties

Detecting Fallback Usage

Best Practices