Upgrade 12->13 stuck due to postgis / raster issue

Greetings,

I recently took over the management of a postgresql + postgis db on aws
rds. Given the age of this project, the db itself is probably ~7-8 years
old. It is currently on v12.12 and I'm unable to upgrade it to 13+. The db
does use postgis, but as far as I can tell, no raster or topology or other
postgis-related fields/features.

When I try to upgrade on aws, I get the following error:

> The instance could not be upgraded because there are one or more databases
with an older version of PostGIS extension or its dependent extensions
(address_standardizer, address_standardizer_data_us,
postgis_tiger_geocoder, postgis_topology, postgis_raster) installed.
Please upgrade all installations of PostGIS and drop its dependent
extensions and try again.

SELECT postgis_full_version(); gives the following (reformatted for
clarity):

POSTGIS="3.1.7 aafe1ff" [EXTENSION]

PGSQL="120"

GEOS="3.8.2-CAPI-1.13.4"

PROJ="Rel. 5.2.0, September 15th, 2018"

GDAL="GDAL 2.4.4, released 2020/01/08"

LIBXML="2.9.1"

LIBJSON="0.13.1"

LIBPROTOBUF="1.3.2"

WAGYU="0.5.0 (Internal)"

RASTER (raster lib from "2.5.5 r0" need upgrade) [UNPACKAGED!] (raster
procs from "2.5.2 r17328" need upgrade)

Note that it lists RASTER both as being unpackaged and needing an upgrade,
even though postgis_raster is apparently not installed. My thinking is that
somewhere along the way, postgis_raster and possibly topology were
installed and later uninstalled (perhaps after being unbundled?).

For more clues, I issued the following command. For clarity I replace the
account numbers with pseudo-usernames for clarity. Also note that schema_1
and schema_2 are two schemas that the project uses.

db=> select a.extname, a.extowner, a.extnamespace, a.extversion, b.nspname,
b.nspowner from pg_catalog.pg_extension a, pg_namespace b where a.extname
LIKE '%postgis%';

extname | extowner | extnamespace | extversion | nspname |
nspowner
---------+------------+--------------+------------+--------------------+----------
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_toast |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_temp_1 |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_toast_temp_1 |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_catalog |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | information_schema |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | extensions |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | schema_1 |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | my_new_topo |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | tiger |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | tiger_data |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | topology |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | schema_2 |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | public |
<local_admin>
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_temp_4 |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_toast_temp_4 |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_temp_5 |
<rdsadmin>
postgis | <rdsadmin> | 16404 | 3.1.7 | pg_toast_temp_5 |
<rdsadmin>

I'm not familiar enough with postgresql nor postgis to understand whether
the nspname entries for tiger, topology, etc. are expected, or offer clues
as to the problem that I am encountering.

Some things that I've tried:

db=> SELECT postgis_extensions_upgrade();
NOTICE: Extension postgis_raster is not available or not packagable for
some reason
NOTICE: Extension postgis_topology is not available or not packagable for
some reason
NOTICE: Extension postgis_tiger_geocoder is not available or not
packagable for some reason
postgis_extensions_upgrade
-------------------------------------------------------------------
Upgrade completed, run SELECT postgis_full_version(); for details

Also:

db=> select * from pg_available_extensions where name like 'postgis%';
name | default_version | installed_version |
comment
------------------------+-----------------+-------------------+------------------------------------------------------------
postgis | 3.1.7 | 3.1.7 | PostGIS
geometry and geography spatial types and functions
postgis_tiger_geocoder | 3.1.7 | | PostGIS
tiger geocoder and reverse geocoder
postgis_topology | 3.1.7 | | PostGIS
topology spatial types and functions
postgis_raster | 3.1.7 | | PostGIS
raster types and functions
(4 rows)

And:

db=> \dx
List of installed extensions
Name | Version | Schema |
Description
---------------+---------+------------+---------------------------------------------------------------------
fuzzystrmatch | 1.1 | extensions | determine similarities and distance
between strings
plpgsql | 1.0 | pg_catalog | PL/pgSQL procedural language
postgis | 3.1.7 | extensions | PostGIS geometry, geography, and
raster spatial types and functions
sslinfo | 1.2 | public | information about SSL certificates
(4 rows)

And:

db=> CREATE EXTENSION postgis_raster;
ERROR: PostGIS Raster is already installed in schema 'extensions'
CONTEXT: PL/pgSQL function inline_code_block line 10 at RAISE

And:

db=> DROP EXTENSION postgis_raster;
ERROR: extension "postgis_raster" does not exist

I also did a snapshot backup and restored to a new instance on aws, and
this resulted in exactly the same problem on the new instance.

So I'm both stuck and confused. It seems that I'm in the middle of a
partial upgrade/install that broke along the way. Does anyone have other
suggestions on what I might try? I'd like to get to v13+ with only postgis
(no raster, topology, etc.) installed without losing any data along the
journey. Is my only recourse to do a full data backup to sql followed by
creating a new instance and restoring data?

Thanks,

->jvp