TL;DR: Starting with Free Edition release 23.26.1, database startup results in ORA-00600 [ksipc: no private ips avail for use] and instance crash if no IPv4 IP address is assigned. This is likely a newly introduced bug as 23.26.0 and below start successfully without a network (minimal networking). Manually adding an IPv4 to the downed interface resolves the problem.
This issue, how to encounter it, and steps to reproduce is described in more detail in the Oracle Database Free forum discussion linked here. As the problem can be reproduced easily and quickly with that edition.
Full output:
$ sqlplus / as sysdba
SQL*Plus: Release 23.26.3.0.0 - Production on Thu Jul 30 17:44:14 2026
Version 23.26.3.0.0
Copyright (c) 1982, 2026, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORA-00600: internal error code, arguments: [ksipc: no private ips avail for use], [], [], [], [], [], [], [], [], [], [], []
SQL>
But this problem affects all editions including Enterprise Edition. And can be reproduced both on-premises and in OCI. By simply removing all assigned IPv4 addresses.
Bottom line is that this is a new ORA-00600 error that affects the latest 23.26.3 database release. And consequently, IMO a new bug should be opened.
I've also opened an Oracle SR to report this but perhaps someone can open a bug based on the information provided here and the above linked forum discussion with the full details?
Thanks,
Simon