ERROR: DBI20122E The instance was not created or updated because the following netname does not exist: "".

The above error might come from different reasons but our case was due to misplaced entries in the /etc/hosts file.

The natural convention for /etc/hosts file is the IP Address FQDN ShortName but some customers especially have a different syntax. They use IP address ShortName FQDN and this has the issue when db2icrt command is run.

If net name for member and CF used in the db2icrt command has FQDN and the /etc/hosts file has IP address ShortName FQDN syntax, then you are likely to get this error.

Two options: Either follow the accepted convention of using proper syntax for /etc/hosts file or do not use FQDN while defining the net names for CF and Member.

Hope this helps someone who runs into this issue.