Django 502 Bad Gateway

I get a 502 Bad Gateway each time I try accessing my web app. It was accessible prior but suddenly started showing a 502 Bad Gateway. My nginx configuration is:

server {
     listen 80;
     server_name IP_ADDRESS;

     location = /favicon.ico { access_log off; log_not_found off; }
     location /static/ {
         root /home/user/pyapps/test_project;
     }

     location /media/ {
         root /home/user/pyapps/test_project;
     }

    location / {
        include proxy_params;
        proxy_pass http://unix:/run/gunicorn.sock;
    }
}

Gunicorn.service

[Unit]
Description=gunicorn daemon
Requires=gunicorn.socket
After=network.target

[Service]
User=user
Group=www-data
WorkingDirectory=/home/user/pyapps/test_project
ExecStart=/home/user/pyapps/venv/bin/gunicorn \
          --access-logfile - \
          --workers 3 \
          --bind unix:/run/gunicorn.sock \
          test.wsgi:application

[Install]
WantedBy=multi-user.target

sudo systemctl status gunicorn.socket gives:

● gunicorn.socket - gunicorn socket
     Loaded: loaded (/etc/systemd/system/gunicorn.socket; enabled; vendor preset: enabled)
     Active: failed (Result: service-start-limit-hit) since Thu 2023-03-30 06:50:20 UTC; 18min ago
   Triggers: ● gunicorn.service
     Listen: /run/gunicorn.sock (Stream)

Mar 30 06:46:29 ... systemd[1]: Listening on gunicorn socket.
Mar 30 06:50:20 ... systemd[1]: gunicorn.socket

sudo systemctl status gunicorn.service gives:

● gunicorn.service - gunicorn daemon
     Loaded: loaded (/etc/systemd/system/gunicorn.service_; disabled; vendor preset: enabled)_
     Active: failed (Result: exit-code) since Thu 2023-03-30 06:50:20 UTC_; 21min ago_
TriggeredBy: ● gunicorn.socket
    Process: 46876 ExecStart=/home/.../pyapps/venv/bin/gunicorn --access-logfile - --workers 3 --bind unix:/run/gunicorn.sock ....wsgi:application (code=exited, status=203/EXEC)
   Main PID: 46876 (code=exited, status=203/EXEC)

Mar 30 06:50:20 ... systemd[1]: Started gunicorn daemon.
Mar 30 06:50:20 ... systemd[46876]: gunicorn.service: Failed to execute command: No such file or directory
Mar 30 06:50:20 ... systemd[46876]: gunicorn.service: Failed at step EXEC spawning /home/.../pyapps/venv/bin/gunicorn: No such file or directory
Mar 30 06:50:20 ... systemd[1]: gunicorn.service: Main process exited, code=exited, status=203/EXEC
Mar 30 06:50:20 ... systemd[1]: gunicorn.service: Failed with result 'exit-code'.
Mar 30 06:50:20 ... systemd[1]: gunicorn.service: Start request repeated too quickly.
Mar 30 06:50:20 ... systemd[1]: gunicorn.service: Failed with result 'exit-code'.
Mar 30 06:50:20 ... systemd[1]: Failed to start gunicorn daemon.

How can I fix the error of “gunicorn.service: Failed to execute command: No such file or directory”.