SRX doesn't succeed in connecting to JIMS server, connection status shows offline.
When the connection status shows 'offline' (show services user-identification identity-management status) it means that the SRX (client) is not able to establish the HTTPS connection with JIMS (server).
HTTPS connection to JIMS server may fail due to multiple reasons such as misconfigurations, connection being dropped in the middle, filters blocking the connection on either direction, invalid certificates etc.
When JIMS application is installed on a machine it comes with a root certificate (PEM format) usually called "JunipercloudsRootCA.pem", when we install the application and go to 'Settings > General" we can see the default configuration used by JIMS to establish the connection with the SRX: Port 443 and the default certificate (which will be used for the TLS handshake). This default certificate is signed and the root certificate we downloaded at the beginning is from the authority that signed it.
If the "JunipercloudsRootCA.pem" CA certificate is being called under [services user-identification identity-management connection primary ca-certificate] it may cause some validation issues when JIMS sends its certificate, usually SAN field failed validations are observed even if this is hardcoded using an FQDN, the reason for this is that the SRX will by default trust the certificate sent by JIMS app and there will be no need for specifying the root CA hence the statement is only optional and not mandatory.
Configure JIMS from the SRX as per https://www.juniper.net/documentation/us/en/software/junos/authentication-firewall/topics/topic-map/security-user-auth-configure-jims.html.
If this doesn't solve the issue consider the above mentioned reasons for this connection to fail, if the issue continues enable identity management traceoptions so that it can be investigated further:
set services user-identification identity-management traceoptions file <filename> files <number of files> size <size of each file> <--Files will be under /var/log, you can use "show log <filename>" to check the contents.
set services user-identification identity-management traceoptions flag all
set services user-identification identity-management traceoptions level all
12/7/2023: Formatting corrections made