But not in v29.0 once it's released
If it won't be capable of converting it as needed, that's a surprise.Quote
Meticulously read every release notes from v0.18.1 to v28.1
Too bad there's no all-in-one changelog.That's what I wanted to add too 
It's only 15 GB, and fits even on a USB-stick.
Yes, though depends on your set prune size. It's only 15 GB, and fits even on a USB-stick.Though I'm wondering more about potential "silent" problems.
In theory, one would expect it to explicitly alert if something's not compatible, leave the data be, and exit gracefully.
Core is typically pretty elaborate in data compatibility checking, and logging / alerting.