PostgreSQL upgrade on Amazon RDS blocked by PostGIS version

Question

I'm trying to upgrade my RDS instance from 9.5.4 to 9.6.1, and I'm getting blocked by an error about the PostGIS version needing to be upgraded first.

Database instance is in a state that cannot be upgraded: PreUpgrade checks failed: The instance could not be upgraded because there are one or more databases with an older version of PostGIS installed. Please upgrade all installations of PostGIS and try again.

The highest version of PostGIS supported by RDS 9.5.4 is 2.2.2

alter extension postgis update

yields

NOTICE: version "2.2.2" of extension "postgis" is already installed

I tried upgrading explicitly to the version in 9.6.1

alter extension postgis update to '2.3.0'

Getting

[Err] ERROR: extension "postgis" has no update path from version "2.2.2" to version "2.3.0"

So my question is: how do I upgrade? I suspect I can delete the extension prior to the upgrade and install the new version after, but I don't know what that will do to my data, or if that will properly upgrade my spatial structures or functions.

I have already checked the documentation for any mention of this scenario

Answer 1

Make sure your instance is upgraded to 9.5.4 before upgrading to 9.6.1.

I had this same error on one of my DB instances, but it was on 9.5.2. First I upgraded it to 9.5.4 and then to 9.6.1 and everything worked as expected.

The next instance I tried it on was already on 9.5.4 and got the same message.

So first I did an:

ALTER EXTENSION postgis UPDATE; 

Then upgraded the server