I wanted to add Agricraft to the AT-Launcher-Modpack R&Q's ENDLESS. Every time when I start the game it is preparing the game files and crashes when reaching the last point of preparing.
Mod-Version: 1.5.0 (also tried 1.2.1)

Could you provide your latest crash report. Without, nobody can help you.

fml-client-latest.txt

Just tried with the 1.4.6 version of the mod and now the world is loading but then it crashes again...

Seems to be a duplicate of #523 .

Try with the latest Botania for 1.7.10 and Agricraft 1.5.0

fml-client-latest.txt

Crashing again while loading :/

That breaks some mods, but not Agricraft's fault anymore:

    UCHE    openmodularturrets{2.2.0-178} [Open Modular Turrets] (OpenModularTurrets-1.7.10-2.2.0-178.jar)
    UCHE    PortalGun{4.0.0-beta-5} [PortalGun] (PortalGun-4.0.0-beta-5.jar) 
    UCHE    Translocator{1.1.2.15} [Translocator] (Translocator-1.7.10-1.1.2.15-universal.jar) 
    UCHE    utilityworlds{1.0.7} [Utility Worlds] (UtilityWorlds-1.7.10_1.0.7.jar) 
    UCHE    denseores{1.0} [Dense Ores] (DENSEORES-1.5.jar) 

Does it work if you try with Botania 237 ?

The second log i provided was with Botania 237.

oops

And with Botania 249 ?

I start tests in my side.

fml-client-latest.txt

Another crash with Botania 249 :(

I have too.
In my side it's a maximum range exceeded. That means there are too many block (obviously too many mods). If the error is the same for you, delete some mods you will not be using to free some space.

@RedNesto is correct.

Worked fine for me - thanks a lot!