I was having a similar problem with the loading of the launcher...it reached 26%. After commiting to the rebuilding fix and it not working three times i almost gave up. However what worked for me though im not sure its a universal fix is that 1. I used a lan cord instead of wireless( way faster cut my time from 4 hours to one) 2. I made sure i deleted alll info of ffxiv including saved data on cloud and system storage and finally 3. once it was downloaded and installed when it was loading the setup in launcher right before it reached 26% for me i clicked on the link for the worlds list hoping somehow id avoid the error 20019....AND IT WORKED!!! Finally playing in world 6 now...hopefully maybe thatll help someone i dunno seems like you almost have to keep deleting/rebuilding/installing to fix but you could try what i did with opening the world list where ever it goes down for you good luck