Java Edition:Loading 1.17 Snapshots
Some 1.17 snapshots conflict with other 1.17 snapshots, and other versions in general. This is due to world generation changes and 1.17 snapshots being largely experimental versions of Minecraft overall. If you're looking to collect all discontinued features in 1.17 and it's snapshots, you'll need this page. This page covers instructions on how to load conflicting 1.17 snapshots and the dangers of doing so.
Dangers
Doing this regularly and for different snapshots will most likely lead to regular crashes and potential world corruption. Make frequent world backups, stay out of chunks that have important stuff so they aren't reset on world loading, back up spawn region if important stuff is there, try to stay in older unimportant chunks, and most importantly, stay out of areas containing other 1.17 generated content, especially chunks from versions with raised world height! This will be very difficult due to your spawn being reset, so it make take a few tries.
How to load 1.17 snapshots
The easiest way to load conflicting 1.17 snapshots is to use World Save Insertion, a simple overview will be provided here, for the full informative article and it's possiblities, see World Save Insertion. The basic idea is to make your world save unplayable by deleting some important files, then forcing the game to generate a new level.dat for it, this will retain your world but reset your player. The basic instructions detailed below are different from the instructions on Loading 1.13 Snapshots due to that method being patched, this is a more complicated work around.
- Make at least one world backup!
- Delete or move the following files and folders in their entirety (moving is suggested if you want to keep any discontinued data contained in these files): "level.dat", "level.dat_old", and "playerdata".
- Go into your files and rename your world save to include a "1" after it. For example, if your world name is "New World", rename it to "New World 1".
- Load up Minecraft and click "Create New World".
- Inside "World Name" type out the exact same name that the world you're trying to load has, but without the "1", this is how we trick the game into generating a new level.dat for the world. To keep with the example it would simply be "New World".
- Set the settings how you want them, its suggested you keep the same seed as your previous world, additional info on seed and setting changes are on Seed Manipulation and World Save Insertion.
- Now go back into your files and remove the "1" from your world save. To once again keep with the example, change your world name from "New World 1" to "New World". The renaming steps are crucial to trick the game into generating a new level.dat, otherwise this will not work.
- Click "Create New World".
Upon world load you should see your world but have a fresh new player and be playing in a previously impossible version.
Help
If you have any problems please refer to the Help page.