Grammarly Common Errors

Error Reference

400 Bad Request — Text Too Short

Cause: Text has fewer than 30 words.

Fix: Ensure minimum 30 words. Pad short texts with context if needed.

401 Unauthorized

Cause: Token expired or invalid.

Fix: Re-authenticate with client credentials grant.

413 Payload Too Large

Cause: Text exceeds 100,000 characters or 4 MB.

Fix: Split into chunks using paragraph boundaries. See grammarly-sdk-patterns for chunking function.

429 Too Many Requests

Cause: Rate limit exceeded.

Fix: Implement exponential backoff. See grammarly-rate-limits.

Plagiarism Check Stuck on "pending"

Cause: Large document processing or service delay.

Fix: Poll every 3-5 seconds, timeout after 90 seconds.

AI Detection — Inconsistent Scores

Cause: Short text produces unreliable results.

Fix: AI detection works best on 200+ words. Scores on short text are less reliable.

Quick Diagnostics

# Test API connectivity
curl -s -o /dev/null -w "%{http_code}" \
  -H "Authorization: Bearer $GRAMMARLY_ACCESS_TOKEN" \
  https://api.grammarly.com/ecosystem/api/v2/scores

# Test with sample text
curl -X POST https://api.grammarly.com/ecosystem/api/v2/scores \
  -H "Authorization: Bearer $GRAMMARLY_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"text": "This is a test sentence that has more than thirty words so that the API will accept it and return a valid writing score for our diagnostic purposes."}' | python3 -m json.tool

Resources

• Grammarly API Support

Next Steps

For debugging tools, see grammarly-debug-bundle.