cant load any worlds

---- Minecraft Crash Report ----
// There are four lights!

Time: 8/30/17 2:04 AM
Description: Starting integrated server

java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $
	at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350)
	at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:80)
	at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61)
	at rc.a(SourceFile:504)
	at rc.a(SourceFile:522)
	at ph.b(SourceFile:177)
	at ph.<init>(SourceFile:63)
	at bib.a(SourceFile:2175)
	at bol.e(SourceFile:229)
	at bol.a(SourceFile:182)
	at bol.a(SourceFile:148)
	at bjm.a(SourceFile:41)
	at bok.a(SourceFile:117)
	at blk.k(SourceFile:400)
	at bok.k(SourceFile:49)
	at blk.q(SourceFile:377)
	at bib.t(SourceFile:1625)
	at bib.az(SourceFile:1000)
	at bib.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 com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350)
	at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:80)
	at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61)
	at rc.a(SourceFile:504)
	at rc.a(SourceFile:522)
	at ph.b(SourceFile:177)
	at ph.<init>(SourceFile:63)

-- Starting integrated server --
Details:
	Level ID: New World
	Level Name: New World
Stacktrace:
	at bib.a(SourceFile:2175)
	at bol.e(SourceFile:229)
	at bol.a(SourceFile:182)
	at bol.a(SourceFile:148)
	at bjm.a(SourceFile:41)
	at bok.a(SourceFile:117)
	at blk.k(SourceFile:400)
	at bok.k(SourceFile:49)
	at blk.q(SourceFile:377)

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

-- System Details --
Details:
	Minecraft Version: 1.12.1
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 1846812120 bytes (1761 MB) / 1939079168 bytes (1849 MB) up to 4080271360 bytes (3891 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn2G
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.12.1
	LWJGL: 2.9.4
	OpenGL: GeForce GTX 1080/PCIe/SSE2 GL version 4.5.0 NVIDIA 385.41, NVIDIA Corporation
	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: 8x Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz