After upgrade to 9.6: waiting column does not exist

We did a pg_upgrade from 9.5 to 9.6

Now, when running the 9.6 server the following error message shows up
regularly in the log:

postgres(at)template1 ERROR: column "waiting" does not exist at character 217

As far as I understand the following remark in the release notes, the
column 'waiting' should not exist:

-

Improve the pg_stat_activity
<https://www.postgresql.org/docs/9.6/static/monitoring-stats.html#PG-STAT-ACTIVITY-VIEW>
view's information about what a process is waiting for (Amit Kapila, Ildus
Kurbangaliev)

Historically a process has only been shown as waiting if it was waiting
for a heavyweight lock. Now waits for lightweight locks and buffer pins are
also shown in pg_stat_activity. Also, the type of lock being waited for
is now visible. These changes replace the waiting column with
wait_event_type and wait_event.

How do I correct this?

Regards
Johann

--
Because experiencing your loyal love is better than life itself,
my lips will praise you. (Psalm 63:3)