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Hello i have been trying to use mods on 1.7.10 but find that when i try to load up forge on the launcher it crashes before the game starts here is the crash report

---- Minecraft Crash Report ----
// Why did you do that?

Time: 18/12/18 01:09
Description: Initializing game

java.lang.NoClassDefFoundError: bxf
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
at java.lang.Class.getField0(Class.java:2975)
at java.lang.Class.getField(Class.java:1701)
at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:203)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:480)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:867)
at net.minecraft.client.main.Main.main(SourceFile:148)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: bxf
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 14 more
Caused by: java.lang.NullPointerException
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182)
... 16 more

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
at java.lang.Class.getField0(Class.java:2975)
at java.lang.Class.getField(Class.java:1701)
at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:203)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:480)

-- Initialization --
Details:
Stacktrace:
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:867)
at net.minecraft.client.main.Main.main(SourceFile:148)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --
Details:
Minecraft Version: 1.7.10
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 86027976 bytes (82 MB) / 167772160 bytes (160 MB) up to 2147483648 bytes (2048 MB)
JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML:
Launched Version: 1.7.10-Forge10.13.3.1374-1.7.10
LWJGL: 2.9.1
OpenGL: GeForce GTX 970/PCIe/SSE2 GL version 4.5.0 NVIDIA 369.09, NVIDIA Corporation
GL Caps: Using GL 1.3 multitexturing.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

Is Modded: Definitely; Client brand changed to 'fml,forge'
Type: Client (map_client.txt)
Resource Packs: []
Current Language: ~~ERROR~~ NullPointerException: null
Profiler Position: N/A (disabled)
Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Anisotropic Filtering: Off (1)

I have reason to believe that this is an issue with java as i am on the latest version but do not know for sure and cannot downgrade to java 7 so any help on how to do this would be nice

From the looks of it, my guess would be an issue with your Java jdk or some issue with your Minecraft itself. You don't mention any mods, so I'm assuming you don't have any installed. First I'd recommend deleting your .minecraft folder and reinstalling Forge to see if that helps. If not, I'd recommend making sure you're on jdk 7, which you can do by going to this link and downloading the proper one for your operating system.

Your Forge is very outdated, update Forge.

Download Forge here: http://files.minecraftforge.net/maven/net/minecraftforge/forge/index_1.7.10.html

thank you both i have solved this by doing a clean reinstall of minecraft and updating forge thank you!

Quote from bigjosephroseph»

thank you both i have solved this by doing a clean reinstall of minecraft and updating forge thank you!

Always happy to help!