It has come to our attention that some people could have malicious intent with the world download, especially if we were to make it available immediately after updating. For this reason, we’ve decided to alter our plan slightly: The 1.12 world will be available for download 3 months after we update to 1.13. If you would like to download your build before this time you may use the Schematica mod (http://bit.ly/2F4BLKs) to download your build as a schematic. Schematics can be pasted into any world or server with WorldEdit.
The Schematica mod also allows you to load a guide in-game showing you exactly where to place all the blocks in order to re-create a build that you have saved. You are welcome to use this feature to recreate your builds in the new world if you would like.
If you need any help with this mod, please see the link above and watch some of the tutorials on there. We do not offer support on this mod.