Upgrading from RoboHelp X3 to 2019

If you have RoboHelp installs/versions between X3 and RH2019 new, you can absolutely do it. I have projects I created in X3, and upgraded incrementally over the years as new RH versions were released (specifically, we had X5, TCS 3.5, TCS 4, RH 2015, RH 2017, RH2019 - and maybe 1 or 2 other versions in between), that have been successfully upgraded to RH2019 New.

However, that's a heavy lift, assuming you can even get access to some of the versions in between (ebay?), so I'd just make a copy of a project, pour yourself a drink, and try taking the copy straight from X3 to 2019 Classic (if that works, pour yourself another drink and try going from Classic to New). Good luck!  

As Jeff said, that is a huge jump.

I would be very interested to learn how well it goes. Please post back when you have completed the upgrade.

Wow - that's a huge jump. Start with a backup and only play with a copy. You'll have to use RH2019 Classic first before trying to move the project to the New UI version. On a non-production machine, I would download a trial copy of RH2019 and test the conversion out.