(Question) Remove Mods Without Shuffling IDs in 1.7.10

[Rasply]

So a friend of mine has been maintaining a custom modpack for a little while now, and on a few occasions he's had to remove mods from the pack. When he does so, he simply deletes the .jar from the Mods folder, tests it out, and updates the pack (I think). However, each time this happens, every single modded item/block ID gets swapped for something completely different, and we have to reset the world.

I get that server wipes happen when you play with modded Minecraft, but I can't help feeling that this is a preventable issue. In fact I've seen it done before, without touching IDs, on other packs. But any searches I've done on the subject have led to threads about dealing with ID conflicts when adding mods  So my question is, for future reference, how do you preserve existing item IDs after removing mods from a custom 1.7.10 pack? Any help or insight is welcome and will be relayed to my friend pronto, cause this pack is getting pretty laggy.

P.S. If you really need to know what the pack is to help I'll PM you it when I get off work this evening so you can check it out, but right now I prefer not to advertise.

[AetherPirate]

Usually this is not a problem, unless it is a heavily tweaked pack with custom recipes. When he re-launches the server after removing mods, whatever worldgen and items that mod added will go away after he /fml confirms. Depending on what he removes, that could break a world, but it should not shuffle up all item ID's

[Rasply]

Just got off work, thanks for the reply.

8 hours ago, AetherPirate said:

Usually this is not a problem, unless it is a heavily tweaked pack with custom recipes.

The modpack in question has an... odd history. It was originally a pack made for and by a specific server, and very tweaked and optimized. The guys who maintained it were masters of their craft, but, long story short, the server eventually closed. The aforementioned friend of mine decided to make his own server with this pack, and did so (with the makers' blessing) by copying the mods, configs and etc. from his client installation to a server one, then removing the client-only stuff. It actually worked well, and he later made a new pack based on it, with a bunch of additional mods. Now we have too many mods, and need to cut back a few to save performance. But, as mentioned in OP, removing mods shuffles all the IDs for some reason.

Apologies for the history lesson, I just hope some insight can be gleaned from knowing how things got to this point. Anyway, to refine my original question; What kind of specific pack tweaks do you think could cause such a bizarre issue, and what could be done to resolve it?

Edited December 21, 2016 by Rasply
Changed text color back to automatic, was previously black.

[AetherPirate]

Could you PM me what that pack is? Really curious now. Plus I'd need specific pack info to be of any real help. 

[Rasply]

Can't seem to message you for some reason, so I'ma just tell you here, it's not a big deal. It's called LueraCraft Test Pack.

[AetherPirate]

Nice pack, it's a bit like mine but much larger, and with more combat mods. 

By any chance was it RotaryCraft, DragonApi, and Geostrata that was removed? Mods are gone but the configs remain. Reika has a warning about improperly removing them here:

https://sites.google.com/site/reikasminecraft/home

Also, if you are looking to trim the pack further, consider removing Stellar Sky. I had it in mine and I loved it, but the performance trade-off was just too great. 

There is also an odd thing in /configs, there are many zipped up config directories that shouldn't be there, adding about 70MB to the pack. 

Edited December 21, 2016 by AetherPirate

[Stone Rhino]

I can confirm the nastiness that happens by removing reika's mods. The FML patch referenced on the link AetherPirate gave will help.

[x2006charger]

Pack owner here. This is my first go-round with making a mod pack. I've been lurking this thread and making notes for what I can do. I do want to say that I've never put draconic, or any of Reika's mods on the live version ( And at this point never will considering he seems to have built that self-destruct into them.)

My update process usually goes like this:  I have a total duplicate of the server ( maps, configs, even server.properties.) I throw the test mods onto that, and run it totally separate from the main server. That's how Rieka's configs came into being there. I tested the mods on the test server, which crashed immediately, never even got to load the world.  Removed the mods ( but forgot the configs.) So the configs ended up getting moved to the live server, but the mods never did.
 

 

I hope this helps, and thanks to you all for coming in here with suggestions. Stellar sky will be removed next update, since I never even got that one to work anyway. ( Sadface)