The SRX generates the following error messages whenever the system generates an SNMP trap:

This article provides a procedure to re-configure the SNMPv3 authentication passwords.

Each SNMPv3 user account requires the username, authentication type, authentication password, privacy type, and privacy password to be configured on the device. After a user enters a password, the SRX  generates an engine ID and password, which are written to the configuration file. After the key is generated, the password that we configured is deleted from this configuration file.

If anyone changes the local-engine configuration (optional configuration for SNMP),  we need to reconfigure the user passwords to generate the key again.  Otherwise the system will generate the following error message:

snmpd[1230]: LIBJSNMP_NS_LOG_ERR: ERR: snmpd: send_trap: USM unknown security name (no such user exists)

Re-configure the SNMPv3 authentication passwords as shown below, so that a new set of keys based on engine ID and password is generated.

set snmp v3 usm local-engine user <UserName> authentication-md5 authentication-password <Password>
set snmp v3 usm local-engine user <UserName> privacy-des privacy-password <Password>