What is the upgrade path?

Any help appreciated,

Archer

As I understand it, the upgrade path is the route you take to get from 5.45 to 6.7.x to 7.3.1

Is it classic or threads you are referring to?

If it's classic, you'll have to upgrade to the last version (6.7.x) and then import to php/MySQL.

Don't be put off by the path, the end result is worth it

True, especially for a version that ancient.

If you run into trouble, I've done that upgrade a few dozen times, pm me if you need help.