Cannot upgrade/restore ArcGIS 10.5.1 geodatabase/PostgreSQL 9.5 to ArcGIS 10.6/PostgreSQL 9.6 when ST_RASTER is installed

Description

The ST_RASTER SQL type was deprecated after the 10.5.1 release. However, its assemblies currently exist in PostgreSQL databases, as the type was installed into the database at a previous release. For PostgreSQL, the following error may be encountered while running the pg_restore utility to restore the sde schema:

[archiver (db)] could not execute query: ERROR:  function sde.subset(sde.st_raster, text, text) does not exist

The Solution section below provides a method to remove the ST_RASTER type and its supporting functions from the geodatabase.

Cause

The ST_RASTER type was installed into the database at a previous release. This error occurs if the sde schema contains the deprecated ST_RASTER type.

 There are no known reports of errors that have occurred due to the presence of the ST_RASTER type in SQL Server or Oracle databases.

Workaround

1. Perform a file system level backup. Refer to the PostgreSQL Documentation for instructions:
   File System Level Backup
2. Use this ArcGIS Desktop document to convert raster data from the ST_RASTER storage type to the RASTERBLOB storage type:
   Convert raster data from ST_Raster to RASTERBLOB storage
3. Remove all raster datasets from the database that have a column with an ST_RASTER type.
4. Use this SQL statement to verify that no columns of type ST_RASTER remain in the geodatabase:

select relname from pg_class where oid = (select attrelid from pg_attribute where atttypid = (select oid from pg_type where typname = 'st_raster'))

5. Connect to the database as the geodatabase administrator, and execute the SQL statements provided in the attached file in the Related Information section below to remove the ST_RASTER type and functions.
   Cut and paste the statements in the attachment into a file and execute them as a script in your PostgreSQL SQL utility.
6. Create a new dump file and restore it using pg_dump and pg_restore to verify that the database can be cleanly backed up and restored without error.