python – Trying to run Flask app gives Address already in use

It means theres another services using that port (8080 in this case). Maybe because you forgot close another running Flask app and its using 8080 port.

However, you could change the port youre using, for example change it to 4444 like this:

if __name__==__main__:n    app.run(host=os.getenv(IP, 0.0.0.0), n            port=int(os.getenv(PORT, 4444)))n

But anyways, I think youd like to know which program is using that part if its not your program. You could use nmap or netcat GNU program to check it.

Heres the netcat way (from here):

$ sudo netstat -nlp | grep 8080ntcp  0  0  0.0.0.0:8080  0.0.0.0:*  LISTEN  125004/nginxn

When you got it, Id suggest stop it manually (for example if its nginx or other HTTP servers, then stop it via service command or systemctl if youre using systemd Linux)

You can also kill it via command kill:

kill <pid>n

You can also kill it via killall or pkill, it use a process name instead of its pid:

killall/pkill <process name>n

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Try to kill all the other processes which are running on your server using this command

n

sudo fuser -k xxxx/tcp

n

replace xxxx with your port name

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python – Trying to run Flask app gives Address already in use

You can get the pid of all running processes having python keyword using the command:

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ps -fA | grep python

n

After getting the pids use kill command as follows:

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kill -9 pid

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After running above two commands now run the flask app, it will work fine

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python – Trying to run Flask app gives Address already in use

python – Trying to run Flask app gives Address already in use

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