What should I do if 'Uncaught (in promise) Error: Network Error' occurs when using axios in a Vue application?

Vue is a popular JavaScript framework that helps developers build dynamic single-page applications. Axios is a Promise-based HTTP client written for JavaScript, used by browsers and Node.js platforms to send HTTP requests. Vue and Axios are a good combination, but in actual application, you may encounter "Uncaught (in promise) Error: Network Error" error. This error is usually caused by problems with axios accessing the API server. In this article, we will explore how to recover the application from this error.

1. Check whether the API server is available

When using axios in a Vue application, the most common thing is to access the API server to obtain data. Therefore, when the error Uncaught (in promise) Error: Network Error occurs, you should first check whether the server is available. You can use the curl command to test whether the API can respond to requests normally. As shown below:

$ curl -X GET http://localhost:3000/api/users
{"status":200,"data":[{"id":1,"name":"John"},{"id":2,"name":"Bob"}]}

If the test fails or the status code returned by the server is not 200, it means there is a problem with the API server and the server problem needs to be repaired.

2. Check the network connection

If the API server is available but still inaccessible, you need to check whether the network connection is normal. An unstable network connection can cause network errors when sending requests to the API server using axios. Use network diagnostic tools such as ping, traceroute or nslookup to check whether the network connection is normal. If there is a network connection problem, you need to try to fix the problem and make sure the network connection is stable.

3. Check axios configuration

axios provides a variety of configuration options to control request behavior. If axios is configured incorrectly, it may also cause the error Uncaught (in promise) Error: Network Error. The following are some common axios configuration options that need attention:

• baseURL: base URL, used to splice the request address.
• timeout: Request timeout.
• headers: Request headers, including Content-Type and Authorization, etc.
• withCredentials: Whether to send cookies to the server.
• responseType: response data type, such as text, json, blob, etc.
• validateStatus: Defines when an HTTP request is considered successful.

Make sure axios is configured correctly and matches the API server.

4. Processing the catch block

Generally, if the axios request fails, a response object will be received, which contains the response error information. If the response is not processed correctly in the catch block, it will cause the error Uncaught (in promise) Error: Network Error. Ensure that response errors are handled appropriately in the catch block and prevent errors from being passed to the next Promise in the Promise chain.

Summary

When an Uncaught (in promise) Error: Network Error occurs when using axios in a Vue application, it may be due to the API server being unavailable, the network connection being unstable, or the axios configuration being incorrect. Correct or the catch block does not handle the error correctly. Using the above suggestions can help you accurately diagnose the problem and restore the normal operation of the Vue application, ensuring that users get the best experience.

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