Supabase Storage Bucket CORS Error on Upload

1. Bucket CORS not configured in Supabase
2. Domain not added to allowed origins
3. Not using public bucket when needed
4. Trying to use private bucket with expired token
5. RLS policy blocks upload operation

Configure CORS in Supabase dashboard > Storage > Buckets > select bucket > CORS policy:

[
  {
    "origin": ["https://yourdomain.com"],
    "methods": ["GET", "POST", "PUT", "DELETE"],
    "allowedHeaders": ["*"]
  }
]

Use signed URLs for private uploads or public bucket for direct uploads.