Issue in python course on youtube

So I was following Mosh’s 6 hour-long python course on youtube and although i followed all the instructions perfectly, during the end of project 3, this error occured.
What do I do?

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Is it possible that the server you were running crashed? Either due to an error or because you closed the terminal or something like that? It looks to me like the server that was running at 127.0.0.1 crashed.

Is there anything in the terminal where you are running the server?