Upgrade RDS Postgres from 11.19 to 15.2 takes enormous amount of time

Question

I am trying to upgrade an RDS Postgres instance from 11.19 to 15.2.
My db is almost empty, with allocated 100GB and used ~1GB.

I would expect the upgrade to be almost seemless, taking at most 5 minutes, but after waiting for more than 1.5 hour, I deleted the instance.

Is there something that I didn't notice that caused this much time of waiting for this upgrade?

Accepted Answer

I found the issue by issuing step by step upgrades for each major version.
When upgrading from latest 11 to latest 12, an error was thrown (and upgrade aborted) about having tables using unsupported WITH OIDS conditions.
After deleting those tables, the upgrade from 11 to 15 took less than 2 minutes (as expected).

However, the issue was that direct upgrade from 11 to 15 did not throw those errors, instead it simply got stuck.

Upgrade RDS Postgres from 11.19 to 15.2 takes enormous amount of time

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