Upgrading a clean 1.40 installation running on postgres to 1.42, I ran into the following warning while upgrading from the cli:

...WARNING: namespace_title still exists, despite it has been renamed into wl_namespace_title (which also exists).
            namespace_title should be manually removed if not needed anymore.

I manually dropped the namespace_title index from the postgres cli after the upgrade process to address this warning.

Logs from the upgrade process attached; first attempt ended in an unrelated exception (T374042), second run completed without error (just the warning).