What should I do if 'TypeError: Failed to fetch' occurs when using axios in a Vue application?

Recently, during the development of Vue applications, I encountered a common problem: "TypeError: Failed to fetch" error message. This problem occurs when using axios to make HTTP requests and the backend server does not respond to the request correctly.

This error message usually indicates that the request cannot reach the server, possibly due to network reasons or the server not responding. What should we do after this error message appears?

The following are some solutions:

1. Check the network connection

Since this error message usually indicates a problem with the network connection, we first need to check this machine network connection is working properly. We can try visiting other websites to make sure the connection is working.

2. Check if the API address is correct

Next, we need to check if the API address requested using axios is correct. We can test directly in the browser whether the API address is working properly. If the API address is incorrect or cannot respond, we need to check the settings of the backend server or contact the API provider for help.

3. Check CORS settings

If we are using cross-domain requests, we need to make sure that the backend server has CORS configured correctly. We can add the following code in the server's code to enable CORS support:

res.setHeader('Access-Control-Allow-Origin', '*');
res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
res.setHeader('Access-Control-Allow-Credentials', true);

If we are using a third-party API, we need to check their documentation to understand how to configure CORS correctly.

4. Check request header settings

Some APIs require specific request header settings to work properly, we need to check whether the request header is set correctly. For example, some APIs require adding an Authorization token in the request header for authentication.

5. Check the backend server status

Finally, we need to check whether the backend server is running normally. We can perform manual testing on the server to confirm whether the server is able to respond to requests. If the server is not responding, we need to check the server's logs to determine what went wrong.

In short, when the "TypeError: Failed to fetch" error message appears, we should first check whether the network connection is normal, and then check the API address, CORS settings, request header settings and back-end server status to find and solve it question.

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