Upgrade from cardano 1.2 to 1.3

i wanna upgrade my server from cardano v1.2 to v1.3, Is v1.3 stable? Is it safe to do it?

Yes. There shouldn’t be any issues upgrading.

You can check release notes before upgrading. The next major version, 1.4, coming around October, might bring some fundamental changes that require you to do some extra work when upgrading, like cleaning the state directory. Stuff like that will hopefully be mentioned in the release notes.