Error Handling

The logic used to detect, manage, and respond to problems safely.

What is it?

Error handling defines what the application should do when something goes wrong.

Good error handling prevents uncontrolled failures and returns useful results.

Simple Definition： Error handling tells the system what to do when an error happens.

Think of an emergency procedure.

When a problem happens, the system follows a planned response instead of failing randomly.

ProblemDetectHandleLogResponse

Catch ExceptionsStop unexpected execution from spreading.

Return Error ResponsesExplain failure to the caller.

Log ProblemsRecord useful debugging context.

Protect DataKeep partial work from corrupting state.

Provide Fallback BehaviorChoose a safe alternative path.

Prevent CrashesFail in a controlled way.

Error handling is used in:

API Routes

Services

Database Operations

External API Calls

Background Jobs

File Processing

Requested order does not exist.

404 Not Found

Response Body

{
  "error": "Order not found"
}

OperationErrorError HandlingLogResponse / Recovery

Error handling turns an unexpected event into a controlled next step.

Decides what the system should do.

It may catch an exception, return a response, retry, recover, or stop safely.

Records information about what happened.

It supports diagnosis, but recording an error alone does not decide the system’s next action.

ENGLISH TERM	中文	SIMPLE ENGLISH	中文小白理解
Error Handling	错误处理	Logic used to respond safely when something goes wrong.	系统发生问题后用于控制和处理错误的一套逻辑。
Error Response	错误响应	A response explaining that a request failed.	后端向客户端返回、说明请求失败的信息。
Exception Handler	异常处理器	Code responsible for handling exceptions.	专门接收并处理异常的代码。
Fallback	备用处理	An alternative action used when the normal path fails.	正常流程失败后使用的替代处理方式。
Recovery	恢复	Returning the system to a usable state.	发生错误后让系统重新进入可正常使用状态。
Graceful Failure	优雅失败	Failing in a controlled way without breaking the whole system.	出错时有控制地返回结果，而不是让整个系统崩溃。

Error handling makes failures controlled.

It works with exceptions, logs, and responses.

Good error handling helps protect system reliability.