Reasons for RRC release from network after registration request by UE

Hi NR Experts.

In NR SA, after registration request sent by UE, if network send RRC release, what can be probable reasons?

UE registration message goes inside RRCSetup and if gNB rejects this message, gNB sends RRCReject.

But your case you are getting RRC Release. Are there any more RRC/NAS messages exchanged between UE and Network before RRC release?

Something from the message not handled by gNB, can be capability, size or previous context.

Yes same I think may be message size issue.

Open trace in n2 interface to get more details, like the colleagues said, many factors can trigger the release.

I would say check SIP messages, Usually if there is a SIP BYE, then its followed by RRC Release (By Network) message. This is what I have seen in my network