To follow up on this: my problem was solved by setting the system config DefaultTasksMax to a higher number. The default was 60, I changed it to 300 and the Node.js app immediately started to work again.
@heppyAndriawan Now that I looked at your problem again, it may be different from mine.
First thing I can point out with your setup is that the Application Root should not be the same directory as Document Root. You can put the app into the httpdocs directory (it doesn’t have to be...
Even better: there is an official example Node.js app provided by Plesk, which I found in this article. You can find the app’s repository here.
Trying this app shows the same result and doesn’t work:
After some page refreshs it turns into this error:
I can confirm this exact problem with a basic hello world Express app (Express "Hello World" example).
Another app suddenly stopped working (the code wasn’t touched, but Plesk installed automatic updates in the meantime). It can’t be started because of a timeout during the “Initialize language...