Ah, okay, I guess Voltz is the cause then. I'll hop over and look if they can fix it. 
I just found it strange that it stopped the forestry recipe from working.
Oh and the log doesn't really show which mod is broken, it just lists the items but the only recipe that results in "GT-ERR-01" instead of "Iron Ingot" was from Voltz.
Hi,
lately I get GT-ERR-01 shown for Iron Ingots that are input for recipes. Here's an example:
Since in this case the problem is with a recipe for a vanilla item I thought I'd best report it here. It seems to look like this for almost all recipes though (especially from other mods). The only recipes except from this are the industrialcraft2 recipes and unchanged vanilla recipes like the piston, there it still says "Iron Ingot".
Most of the recipes appear to still be working (I just started playing in this world so I didn't get very far but I was able to craft an iron pickaxe with the recipe shown above, it accepted the iron ingot as input). I was unable to craft a Miner's Backpack (Forestry) though. The recipe for it appears in NEI but when I put iron ingots in the appropriate places (where it says "ERROR! PLEASE CHECK YOUR LOG FOR 'GT-ERR-01'! 265" and the other materials in their places it doesn't work. Disabling Gregtech allows me to craft the Miner's Backpack, I checked it in a new world though, because I didn't want the GT ores to despawn.
I'm using:
Minecraft 1.7.10
Minecraft Forge 10.13.4.1614
Gregtech 5.09.29
Forestry 4.2.16.64
Industrialcraft 2.2.827
and a bunch of other mods.. (should I list them all?).
