My version of WP is too old to upgrade…

Hi guys,
I’ve had a website lie dormant for a couple of years, and I’m now coming back to it with a fresh new site, new domain, but my old version of WP (3.8.12) is giving an error message when I try to upgrade it through my Hosting manager. Any migration tools/workflows?

I’d love to keep the old data if I can – there’s quite a bit.

Thanks in advance! 🙂