You should have verified before such an important operation linke upgrading to 10.15: it's been ages 10.14 is warning about the end of support to 64bit software. Not only that, but it's not a good idea to install immediately a new O.S.: I'm waiting at least the .2 release, especially in this case where a lot of 32bit software will be useless. But I don't even know if I'll use it. Probably I'll do a partition only for it and I'll leave my 10.14 as it is. I foresee a lot of software "issues" (but it's not a real issue: simply you won't never again able to use 32bit software).
Use the universal OWIF (OpenWeb Interface) that does everything.