I'm trying to migrate my 1.8.9 world to 1.9. Both use recommended Forge versions. Getting the following warning in the process:

 

Forge Mod Loader detected missing blocks/items.

minecraft:lit_furnace

 

And in the client log:

 

...

[16:54:56] [server thread/INFO] [FML/]: Found a missing id from the world minecraft:lit_furnace

...

[16:54:56] [server thread/ERROR] [FML/]: There are unidentified mappings in this world - we are going to attempt to process anyway

[16:54:56] [server thread/ERROR] [FML/]: Unidentified item: minecraft:lit_furnace, id 62

...

 

What causes this problem and how serious it is? Any chances to get a corrupted world?

 

Thank you,

Full log can be found at http://ipros24.ru/wp-content/uploads/2016/06/fml-client-latest.log.

 

if there are any furnaces that are processing something, go to 1.8.9, stop them (and wait to their fuel go down) and try migrating again.

That's a good suggestion, but how can I find this lit furnace? It's definitely not on the frequently visited chunks. Probably something long forgotten in a temporary underground base.

Try MCEdit

It used to be a problem to install on my platform but I'll try again. Thanks.

1.9 removed the item form of the lit furnace because it's not meant to be used by players, only the furnace itself should switch to that block.

 

This is just telling you that the item no longer exists, blocks in the world won't be affected.

This is the full text of the warning:

 

Forge Mod Loader detected missing blocks/items.

There are 1 missing blocks and items in this save.

If you continue the missing blocks/items will get removed.

A world backup will be automatically created in your saves directory.

 

Missing blocks/items:

minecraft:lit_furnace

 

And this leaves an impression that the conversion WILL affect the blocks of the world. Have no idea where I could get a lit furnace as an item. This is a survival world.

 

The confirmation GUI is less detailed than the log message, it just tells you the total number of missing blocks and/or items and which ones are missing without telling you what each missing thing is.

 

In this case, it's just one item (

minecraft:lit_furnace

) and no blocks missing.

 

Forge saves a list of every block/item name and the corresponding numeric ID with the world. It will detect when a block/item no longer exists, even when it's not used anywhere.

 

If you don't have any Lit Furnaces in item form, nothing will happen to your world. The Lit Furnace block still exists, so furnaces in the world won't be affected.

Ok. Thanks. I hope you're right. Don't have much choice anyway. Will keep the backup for a while in case something breaks later down the road.