Problem with spawn + Electron (backend + frontend ) NODEJS - vue.js

Question

On baackend I have the following modules:
express for event-stream with backend ->frontend
and req/res frontend->backend get /post
Frontend: Electron+vue+axios
When developing an application, I run both parts separately from each other and everything works well.
But in production, frontend runs as a child process of backend
const child = spawn('backend.exe', {
detached: true
});
child.unref();
Over time, and sometimes almost immediately, the backend stops responding.
When opening devTools, I see that all get/post requests are in the cancel status, but the child process is alive, and if the parent process is closed, the child is also closed by processing
app.on('will-quit', () => {
child.kill('SIGTERM')
process exit(0);
});
If you terminate the backend process and remove it from the parent thread by running it separately, then everything works fine.
I also tried to start the backend through exec, in this case everything also works fine, but exec does not provide properties for killing the process when updating the Electon application
How to deal with this spawn behavior?
Why do requests stop coming?
How can I terminate a child process started with exec? child.kill('SIGTERM') doesn't work for exec in app.on('will-quit', () => {...}) event