For issues you find with the Switch and Console releases, please follow this link and give as much detail as possible. This is the speediest way to get info to Pipeworks and get a hotfix in the works.
1.4 will bring many changes to the PC version. We strongly advise making plans to back up your worlds and players prior to updating your game. More details here.
Begin your search for Journey's End information here and here. Please report bugs and issues for Journey's End here.
For issues you find with the Mobile 1.3 update, please follow this link and give as much detail as possible. This is the speediest way to get info to DR Studios to look at your issue. Also, some troubleshooting hints here.
The first thing you should know is now the corruption/crimson spreads to plain rock. This is important as plain rock makes up around three quarters of the world. It also spreads to jungle grass, normal grass, and sand/sandstone, making your world about 90% corruptible. Also the new biome, the Hallow, does the same, aside from the jungle thing. Further, while every biome now has harder enemies, the Jungle is now flush with them, as is the Underground Desert. They now occupy about the same place in Hardmode they did in Normal as far as difficulty, while Hell is, for now, actually pretty safe relatively, there are no new enemies there.
So the first thing you want to do, is find the edges of the new coruption/crimson and Hallow, both sides. Killing the WoF generates big slanting lines of them fromthe top of your world to the bottom, and they spread from their borders. Dig out tunnels along those borders (they won't be very straight) from the surface to hell, at least five blocks wide at every point. Bombs help. Keep your eyes open for mimcs, especially the big ones, they hold great treasures, but are tough as nails, and will kill you.
This job shoul dnet you materials for some new weapons, and likely a bit of the new ore if you have smashed some altars. Keep in mind that smashing the altars may unleash more corruption, crimson, or hallow somewhere random in the world to be contained.