7 Types of Critical Bugs That Frequently Cripple Enterprise Systems

Manual vs Automated: Two Very Different Debugging Approaches

7 Types of Critical Bugs We Encounter Most Often

• ①
  Race Condition on Financial Transactions: Two checkout requests arriving at the same millisecond result in duplicate orders or double stock deductions that ruin inventory accuracy.
• ②
  Memory Leak in Node.js Server: Database connections or event listeners never disposed, causing server RAM usage to creep upward until the server finally crashes after several days of operation.
• ③
  Unhandled Promise Rejection: Async code without try-catch blocks causing silent errors not logged, yet leaving data in a half-saved, corrupt state.
• ④
  N+1 Query Problem: A product listing page running 1 main query + 1 extra query per product. With 100 products, this becomes 101 database queries every time the page loads.
• ⑤
  Null Pointer Exception from External API: Code assumes the API always returns complete data. When a field is missing (null), the app throws an error and crashes directly in production.
• ⑥
  CSRF & XSS Vulnerabilities: Forms without CSRF tokens are vulnerable to cross-site attacks. Unsanitized HTML output opens gaps for malicious script injection into users' browsers.
• ⑦
  Circular Dependency Import: Module A imports Module B, and Module B imports Module A. In TypeScript, this often goes undetected during development but causes mysterious undefined errors in production.