Sometimes, in the close queue, I find some post that is flagged as off-topic becase too old to migrate. The most recent is What was the first trailer to use “in a world”?.
What does it mean?
Exact term is off-topic because… (too old to migrate).
They need to be read separately.
First someone voted it for being off-topic because…, to know the reason of being off topic click on it and new popup will show it.
(too old to migrate) part of it is to highlight to close voters that it can't get migrated anymore because of 60 days rule.
You will see this notice when closing a question that is older than 60 days.
Generally, any post that is older than 60 days and is off-topic will not be migrated (only applicable to off-topic questions) to another SE site where it is on-topic. This migration was disabled because
They're rarely welcomed or heavily improved post-migration, often overtly disliked by folks on the destination site, and can end up causing a rather bad experience for folks who were participating in good faith on the original.
This notice is for notifying Close Voters and Moderators that the respective post cannot be migrated.