My sons game keeps crashing after you hit create world. I've tried the repair option, I've reinstalled and game still crashes. Thanks

– Minecraft Crash Report ----

// I blame Dinnerbone.

Time: 6/29/17 2:24 PM
Description: Updating screen events

java.lang.RuntimeException: Failed to check session lock, aborting
at bez.i(SourceFile:64)
at bez.<init>(SourceFile:50)
at bew.<init>(SourceFile:21)
at bex.a(SourceFile:84)
at bhz.a(SourceFile:2159)
at bog.a(SourceFile:212)
at bli.a(SourceFile:334)
at bog.a(SourceFile:352)
at bli.k(SourceFile:397)
at bli.q(SourceFile:374)
at bhz.t(SourceFile:1625)
at bhz.az(SourceFile:1000)
at bhz.a(SourceFile:419)
at net.minecraft.client.main.Main.main(SourceFile:123)

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

– Head –
Thread: Client thread
Stacktrace:
at bez.i(SourceFile:64)
at bez.<init>(SourceFile:50)
at bew.<init>(SourceFile:21)
at bex.a(SourceFile:84)
at bhz.a(SourceFile:2159)
at bog.a(SourceFile:212)
at bli.a(SourceFile:334)
at bog.a(SourceFile:352)
at bli.k(SourceFile:397)
at bli.q(SourceFile:374)

– Affected screen –
Details:
Screen name: blp
Stacktrace:
at bhz.t(SourceFile:1625)
at bhz.az(SourceFile:1000)
at bhz.a(SourceFile:419)
at net.minecraft.client.main.Main.main(SourceFile:123)

– System Details –
Details:
Minecraft Version: 1.12
Operating System: Windows 8.1 (amd64) version 6.3
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 166258824 bytes (158 MB) / 239120384 bytes (228 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.12
LWJGL: 2.9.4
OpenGL: AMD Radeon HD 7340 Graphics GL version 4.5.13399 Compatibility Profile Context 15.201.1151.1004, ATI Technologies Inc.
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: English (US)
Profiler Position: N/A (disabled)
CPU: 2x AMD E2-2000 APU with Radeon(tm) HD Graphics