When encountering the error message "Network file descriptor is not connected," it's essential to understand its root cause. This common issue arises when attempting to communicate through a socket that does not have a valid network connection.

The error can be attributed to various factors, including forgetting to call the connect function in programming languages like C or Python, network connections being interrupted due to failures or server shutdowns, and file descriptor reuse issues.

To resolve this error, it's crucial to carefully check network operation code to ensure that sockets are correctly connected to target servers. Additionally, adding appropriate error-handling mechanisms can help detect connection interruptions and re-establish connections when necessary.

Source: https://dev.to/carrie_luo1/guide-to-addressing-network-file-descriptor-is-not-connected-4c33