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Even the best-built templates can fail - especially when working with automation, dynamic data, and After Effects. This guide explains how to detect, interpret, and fix common job errors in Nexrender Cloud.

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Where Errors Appear

When a render job fails, the system sets its status to "error". You can detect this in two ways:

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Webhook Delivery

If you’ve defined a webhook, the error will be delivered as a POST request to your endpoint: 
{
  "id": "01JTRDF7HCR8QAHYW8GPCP4S9Y",
  "status": "error",
  "stats": {
    "errorAt": "2025-08-14T09:12:45.799Z",
    "error": "Layer 'title' not found in composition 'main'"
  }
}

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Manual Polling

Poll GET /jobs/{id} and check the status field: 
curl -X GET https://api.nexrender.com/api/v2/jobs/JOB_ID \
  -H "Authorization: Bearer YOUR_API_KEY"
When the job has failed, the response will include "status": "error" and a stats.error string describing what went wrong.

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Common Causes of Render Failures

CauseError Message ExampleHow to Fix
Invalid layerNameLayer 'subtitle' not foundCheck actual layers via GET /templates/{id}
Missing compositionComposition 'main' not foundVerify the composition name via template introspection
Missing asset URLAsset failed to download (403)Double-check src links and access permissions
Font not foundFont 'CustomFont-Bold.ttf' not availablePreload the font using the Fonts API
Broken AE projectRender failed: AE crashed with exit code 1Preview manually inside After Effects
Expression failureAfter Effects expression error at line XSanitize all dynamic input before injecting
Most errors are caused by bad data or structural mismatches between the template and the job payload.

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Debugging Strategy

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Inspect the Template First

Use GET /templates/{id} to see available compositions, layer names, and properties before submitting a job: 
curl -X GET https://api.nexrender.com/api/v2/templates/TEMPLATE_ID \
  -H "Authorization: Bearer YOUR_API_KEY"
This lets you verify exact layer names and composition names before your job runs.

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Use Preview Mode

Render the job with "preview": true to get a fast, low-resolution output that reveals most structural issues before committing to a full render: 
{
  "template": { "id": "YOUR_TEMPLATE_ID", "composition": "main" },
  "preview": true
}
Preview mode catches missing layers, layout bugs, and expression crashes cheaply.

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Isolate with a Minimal Payload

Temporarily reduce your job to the simplest possible payload:
  • Static text only
  • No image or audio layers
  • Known-good composition name
Once that succeeds, reintroduce dynamic elements one at a time until you find the failure point.

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Best Practices for Stability

  • Fetch template metadata via GET /templates/{id} before building any job payload
  • Use descriptive, unique layerName values and document them alongside the template
  • Preload all fonts via the Fonts API before submitting jobs that reference them
  • Validate all asset URLs return 200 OK before sending a render job
  • Wrap dynamic layers with fallback expressions inside After Effects
  • Make your webhook handler idempotent and log every incoming payload for auditability