As the title says. I recently finished compiling all the mods I wanted into my Modpack. (1.12.2) But now im faced with crashes, during initialization and loading. Any help is appreciated. The first few times I loaded my modpack BiblioCraft and The Midnight were the mods to crash my game, but there could be others..
1.Always check for libraries required for mods. Otherwise in crash reports if it's clear that a mod has "errored", for 1.12.2 that would be it says LCE rather than the LC and the other letters showing the stage the mod got to when loading, look to that, otherwise if it's more hard to tell look for mod names in the other output areas of the report. That's what I do. I'm an average programmer when it comes to Java and I don't make mods or know the much about these reports but I just pick out what I can that is readable to anybody or just 1 by 1 add mods to see what happens when making modpacks or putting mods in a mods folder when I'm selecting mods I want to review.
2.Some mods can conflict, try removing or disabling (the option on the left of the mod listing or by renaming the mod's name with .disabled after the .jar). Otherwise if the Mod Dev still supports 1.12.2 versions of their mods, report the crash reports, if not then just use mods you prefer to be in there over the other.
3.If you can't work out what is conflicting, add mods 1 by 1 instead of just having them all included. It is tedious but effective to narrow the one that doesn't want to work with any of the others you have included. I always do this for my modpacks, even if I have reviewed many of them and have experience with them in the instance I have them stored in for review, or when adding them later to the custom modpacks or knowing that a lot of them work if it's part of a Let's Play and I'm making a fan version, conflicts can still happen in any of those three situations.
I can't say for items/blocks/mobs, etc. that conflict but if you can then go for it, otherwise just go with removing the mod or if there is modules like with Buildcraft (though I know it's not the case with Bibiliocraft or Midnight) then choose those. That or use other mods, there is many mods out there besides the ones you see on the popularity filter of Curseforge that can do what Bibliocraft can do for 1.12.2, much smaller ones that have specific features and do the same thing, or sometimes better, not 'all' features but if you want shelves and other features then sure but the enchanted book copying one not likely. Cases like that I find work out too, but I'm more into using mods like that than the big ones and have done so a lot over time as I like to branch out or find alternatives then just the same 10 mods. Specifically as I review mods.