The received data is wrong... fork: retry: Resource temporarily unavailable

Issue

The following error is displayed when opening the Node.js app:

The received data is wrong. Contact support for resolution. /usr/share/python-cllib/da_userdomains: fork: retry: Resource temporarily unavailable
...
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)\n", "result": "json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)\n", "timestamp": XXXXXX}

The error is not a server-wide issue, and it may only be present to one user. It results in the inability of using the Node.js app.

Environment

• CloudLinux OS
• DirectAdmin
• Node.js

Cause & Solution

The issue is caused by the user reaching its NPROC limits. When this limit is reached, no new process can be created, which causes the "Resource temporarily unavailable" error. It is usually caused by hanging processes that have been running for days. The solution is to kill unnecessary processes. The error will be corrected right away. 

Useful links

• NPROC limit
• Node.js Selector