Error 554 is an error opening a socket for network communication. There are many different reasons for this error to occur and obtaining the extended error is essential in understanding the problem.

The extended error will give you more information. For Windows the extended error code will be a Windows system error code and for Linux/macOS this will be the system error code: errno.

For example extended error 24 on Linux is EMFILE, which indicates that the process has too many open files. This could be caused by a bug in your code. Alternatively you could use ulimit to increase the limit.