max(dot)valjanski(at)gmail(dot)com writes:
> Trigger function stopped working after upgrade from 9.5 to 9.6. Upgrade was
> performed via pg_upgrade.
After further thought I suspect this is the same issue discovered earlier
this month:
https://www.postgresql.org/message-id/flat/83shraampf.fsf%40is-it.eu
There's a patch here:
https://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=f4d865f22
If you're not prepared to rebuild with the patch, I think the only
short-term workaround is to recreate the table without a dropped
column.
regards, tom lane