I have some problems。the kamailio version is 5.3.0. My linux version is centos 7. the kamailio log: ERROR: <core> [core/tcp_main.c:3508]: send_fd_queue_run(): send_fd failed on socket 63 , queue entry 1, retries 90, connection 0x7ff46e6b1b60, tcp socket 218, errno=11 (Resource temporarily unavailable) ERROR: {1 12529 MESSAGE 359bf0410a7e471c950623e3f7a3b17b} <core> [core/kemi.c:94]: sr_kemi_core_err(): 202->408 CRITICAL: <core> [core/tcp_main.c:4218]: send2child(): tcp child 6, socket 65: queue full, 291 requests queued (total handled 10665748) This problem does not happen every time。When the number of user registrations increases significantly, errors will appear。I tried to set the parameter tcp_children is adjusted to 8, it will not appear frequently, but when the number of user registrations increases to about 5000, errors will still appear. My kamailio.cfg global parameters are set as follows：tls_max_connections=65536,tcp_max_connections=65536,open_max_files=65536。 -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/kamailio/kamailio/issues/2806