Error upgrading from RDS Postgresql 9.5 to 9.6

Today I was trying to upgrade from postgresql 9.5 to 9.6 and it error out with the following error:

Database instance is in a state that cannot be upgraded: GRANT ALL ON DATABASE "XXXX" TO "XXXXX"; psql:pg_upgrade_dump_globals.sql:106: ERROR: permission denied for database XXXX

Any ideas on how I can proceed?

Thanks