Sometimes Ignite may crash and as a result not properly clean up its connection to the repository database. You may see a message similar to below because the new instance of Ignite thinks the original instance is still running. This is a safeguard to make sure Ignite does not startup twice:

 

To fix this, login to the Ignite repository database as the Ignite user and run the following:

update conprm set v=’STOPPED’ where p=’IDC_STATUS’;
delete conprm where p=’IDC_WIZARD_URL’;

Restart Ignite and it should be able to connect.