Talend Administration Center requires a new installation, please follow the migration chapter in the Talend Migration Guide.
The ESB related pages in Talend Administration Center 6.2 are not backward compatible with older versions of the containers except the ESB Conductor, which still supports the deployment and undeployment of tasks into 6.1.x, 6.0.x, 5.6.x and 5.5.x containers in addition to 6.2 containers.
Please also consider to use the new Migration page in the Administration Center to compare the project before and after migration.