Overview of Amazon RDS Extended Support
After the RDS end of standard support date, if you didn't disable RDS Extended Support during the creation or restoration of your DB instances, then Amazon RDS will automatically enroll them in RDS Extended Support. Amazon RDS automatically upgrades your DB instance to the last minor version released before the RDS end of standard support date, if you aren't already running that version. Amazon RDS won't upgrade your minor version until after the RDS end of standard support date for your major engine version.
You can create new databases with major engine versions that have reached the RDS end of standard support date. RDS automatically enrolls these new databases in RDS Extended Support and charges you for this offering.
If you upgrade to an engine that's still under RDS standard support before the RDS end of standard support date, Amazon RDS won't enroll your engine in RDS Extended Support.
If you attempt to restore a snapshot of a database compatible with an engine that's past the RDS end of standard support date but isn't enrolled in RDS Extended Support, then Amazon RDS will attempt to upgrade the snapshot to be compatible with the latest engine version that is still under RDS standard support. If the restore fails, then Amazon RDS will automatically enroll your engine in RDS Extended Support with a version that's compatible with the snapshot.
You can end enrollment in RDS Extended Support at any time. To end enrollment, upgrade each enrolled engine to a newer engine version that's still under RDS standard support. The end of RDS Extended Support enrollment will be effective the day that you complete an upgrade to a newer engine version that's still under RDS standard support.
For more information about the RDS end of standard support dates and the RDS end of Extended Support dates, see Supported MySQL major versions on Amazon RDS and Release calendar for Amazon RDS for PostgreSQL.