ID Mismatch VS ID Conflict

[Physicist]

When updating mods I've noticed that sometimes I get ID conflicts, sometimes ID mismatches, and sometimes both.

I haven't ever had any trouble going through configs fixing ID conflicts when I add new mods or when an updated mod needs a little more ID space. No problems there at all, and I understand this completely.

Now ID conflicts with a savegame are confusing. I updated Biomes O' Plenty and added Thermal Expansion 3, then fixed the ID conflicts that BOP created within it's own config. I don't see the ID mismatch errors until I try to load a savegame, but it *does* still allow me to load said savegame if I want to.

What's the significance of this, and why did any IDs at all change besides the ones I deliberately changed?
Do I need to worry about this?
Will I (after weeks of progress) find that noticeable blocks are completely gone?

 

[Ashzification]

FTB Tech Support isn't the place to back asking about a modpack that you've made (as evidence by, we don't have any 1.6.4 packs yet), since it's not an issue with FTB. Post on the MCF, or in Mod Discussion on these forums.

 

[Lathanael]

Normally a mismatch is produced when the unlocalized name of an Item/a Block is changed.
This is caused mostly by:

• Configs changed so now a completely different block/item uses the ID in question
• The mod just changed the name of the block/item but it is still the same block/item (for example: you got a name like coalBlock and it gets changed to blockCoal)

If the 2nd is the case you can most of the times ignore the mismatch as nothing really changed except the name of a block/an item.
Now there are other circumstances which i can not remember right now which can cuase a mismatch but the 2 i mentioned are the most common ones.

 

[Jadedcat]

Keep a backup of your world and then go ahead and load and see if anything looks odd. If everything is normal its fine. Quite a few mods have been renaming their blocks lately in code causing those to pop up.

 

[Physicist]

So I discovered the specific ID Mismatch between Biomes O' Plenty 1.1.2 and 1.1.3: They changed leaf blocks. So a save updated from one version to the other will have all old trees stripped of leaves (or if you change the IDs the other way around, replaced by hives or stair blocks of some kind). I presume that my previous encounters with an ID mismatch were minor things, but this is just too much. I think I'll have to restart my 1.6.4 world if I want to add Thermal Expansion 3.

So now I know. Thanks for the help, all.

Ash, sorry about the mis-post. I hadn't realized the specific nature of this forum.