The problem

To explore the
The problem of Proxy error is because the port number is occupied. There are 500 problems in the front end, indicating that there are problems in the back end server, not the proxy in the front-end vue.config. Check that the port number on the back end matches the port number on the front end.

Back end:
where the test environment is called. But the front start local environment,

Fix:
changes the test environment to local

It will run normally
Common web code
Popularize some common signs:

100: Continue
200: Success
400: error requests
401: Unauthorized
403: Server rejects request, prohibits
404: Server could not find the requested page
405: Suppressing the method specified in the request
408: Request for timeout
414: The requested URL is too long for the server to process.
500: Internal server error
505: Server does not support the version of the http protocol used in the request

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