So I created a world a while back using mods with the version 1.7.10. I accidentally clicked on the world using the latest version of Minecraft which is 1.12.2, and cannot open the world using 1.7.10. The game crashes and sends me back to the Minecraft launcher saying that I am using an unsupported modified version of the game.
How do I change my world back to the 1.7.10 version? Thankyou.
Unfortunately, by loading your modded world in 1.12.2 you basically ruined it; even if you could go back all modded blocks and all items (even vanilla ones) will be gone - the only fix is restore it from a backup:
While the link mentions going from 1.8 to an older version this also applies to older worlds that were loaded in 1.8+ then reverted, and even more so, later versions; for example, in 1.11 they changed the IDs for most entities so they too will be gone if you go back, and numerous other changes have been made to IDs and NBT data since 1.7.10.
It might be possible to save the world by using MCEdit to change back every single block/item/entity/etc that 1.12.2 changed but I doubt anybody has made the converter to do this, and since you tried loading it in 1.7.10 it likely caused further damage. One bit of good news is that only chunks within the spawn chunks and around where you were will be affected, and perhaps 1.7.10 had only loaded a few chunks and/or didn't save them before it crashed (so nothing important was removed), but the issues with reverting the changes that 1.12.2 did remain.
For future reference, always run modded and different vanilla versions in their own profiles and in their own game directories and double-check that you are in the right version before playing, and always keep backups for anything you care about (suppose one day your computer refuses to start and indicates a disk failure, or the power goes out while playing, or you get malware, your computer gets stolen, and so on).
Thank you for responding. Next time I'll be definitely creating a backup since I didn't create one with my modded world. I hope one day Mojang will add a feature to PC edition, where the world doesn't save unless you press save and quit so nothing like this happens again.
So I created a world a while back using mods with the version 1.7.10. I accidentally clicked on the world using the latest version of Minecraft which is 1.12.2, and cannot open the world using 1.7.10. The game crashes and sends me back to the Minecraft launcher saying that I am using an unsupported modified version of the game.
How do I change my world back to the 1.7.10 version? Thankyou.
Unfortunately, by loading your modded world in 1.12.2 you basically ruined it; even if you could go back all modded blocks and all items (even vanilla ones) will be gone - the only fix is restore it from a backup:
https://www.minecraftforum.net/forums/minecraft-java-edition/recent-updates-and-snapshots/2201993-so-what-happens-if-you-create-something-in-1-8-and
While the link mentions going from 1.8 to an older version this also applies to older worlds that were loaded in 1.8+ then reverted, and even more so, later versions; for example, in 1.11 they changed the IDs for most entities so they too will be gone if you go back, and numerous other changes have been made to IDs and NBT data since 1.7.10.
It might be possible to save the world by using MCEdit to change back every single block/item/entity/etc that 1.12.2 changed but I doubt anybody has made the converter to do this, and since you tried loading it in 1.7.10 it likely caused further damage. One bit of good news is that only chunks within the spawn chunks and around where you were will be affected, and perhaps 1.7.10 had only loaded a few chunks and/or didn't save them before it crashed (so nothing important was removed), but the issues with reverting the changes that 1.12.2 did remain.
For future reference, always run modded and different vanilla versions in their own profiles and in their own game directories and double-check that you are in the right version before playing, and always keep backups for anything you care about (suppose one day your computer refuses to start and indicates a disk failure, or the power goes out while playing, or you get malware, your computer gets stolen, and so on).
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?
Thank you for responding. Next time I'll be definitely creating a backup since I didn't create one with my modded world. I hope one day Mojang will add a feature to PC edition, where the world doesn't save unless you press save and quit so nothing like this happens again.