I’m not a DBA, but a little more info is available in the Adabas Messages and Codes, Nucleus Startup Messages.
If you asked for access to documentation for your TechCommunity user id, then this link should get you there.
Otherwise, if you have your site’s Empower password, all documentation is there as well.
If neither available at the present, here are the relevant messages:
A nucleus entry already exists in the data integrity block (DIB) for one of the following reasons:
An attempt was made to start a nucleus while another update nucleus was still active; or
The previous nucleus session terminated abnormally but the "nucleus" DIB entry was not removed.
If a DIB entry remained after an abnormal termination, rerun the job with the ADARUN IGNDIB=YES parameter. If the FORCE=YES parameter had been applied, then the nucleus must be started with FORCE=YES and IGNDIB=YES. Here the DIB entry will only be removed once the ID Table initialization had been successful. Running with IGNDIB=YES alone will result in a PARM-ERROR 26.
Interregion communication could not be established.
This message should be preceded by message ADAM98. If the ADAM98 error reason is “DUPLICATE ID (LOCAL)” and a previous nucleus ended such that it was not able to clean up, you may wish to restart specifying FORCE=YES. Refer to ADAM98 message documentation for information about other possible errors.
If IGNDIB=YES was specified, then the nucleus must be started with FORCE=YES and IGNDIB=YES. Here the DIB entry will only be removed once the ID Table initialization had been successful. Running with FORCE=YES alone will result in a PARM-ERROR 23.
Specifying FORCE=YES with the DBID of a currently active nucleus can disrupt operations on that nucleus. In addition, users of the old database whose ID is overwritten by the FORCE=YES option lose access to the database. Therefore, FORCE=YES should only be specified if absolutely necessary . For more information, refer to the FORCE parameter description in the Adabas Operations documentation.
I have no idea if changing the parameters is all that needs to be done, or how to tell which is the reason, an update nucleus already running, or the previous session terminated abnormally. I the latter, it seems like some type of recovery process or utility might be needed to verify or recover the database.
Utilities like ADACHK or ADAICK might tell you what state the databases are in.
Hopefully an experienced DBA or 2 will weigh in on this and provide more informed suggestions.