Mods not working

[JustTired]

My friend and me wanted to play on a modpack, i could play perfectly, i sent my friends the mods, it went perfectly ,HOWEVER i invited my other friend and sent him the exact mods, the exact same version and also the same forge version but he still can not join and it says that the mod versions are wrong everytime he tries joining the server  however we have the same as he does.

[JustTired]

Whats a debug.log, because it just said that all mods are the wrong version even tho were using the same mods. 
 

[Luis_ST]

5 minutes ago, JustTired said:

Whats a debug.log

it's a file which is generated by the game, it contains information about the game start
the file is necessary to help you

you find it in:

• server: server_folder/logs/debug.log
• client: .minecraft/logs/debug.log