Hello Lukasz,
the best advice I can give you is to backup everything and proceed with the installation, then check if your website exploded. : ) Jokes apart, we are not aware of particular issues that may arise, however when upgrading between different major versions, it’s always a best practice to try it first on a staging account, if available, or have ready a fresh backup in the case something doesn’t work afterwards. It should be ok, though.
Thanks,
Michael