When I open fabric 1.16.1, it crashes after the launcher finishes readying the game for launch. It says runtime error in the launcher.
Here is the error:

---- Minecraft Crash Report ----
// My bad.

Time: 7/6/20 7:02 PM
Description: Initializing game

java.lang.RuntimeException: Could not execute entrypoint stage 'client' due to errors, provided by 'resourcepackorganizer'!
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke0(EntrypointUtils.java:53)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke(EntrypointUtils.java:36)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointClient.start(EntrypointClient.java:33)
at net.minecraft.class_310.(class_310.java:425)
at net.minecraft.client.main.Main.main(Main.java:177)
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.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:192)
at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:140)
at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:26)
Caused by: java.lang.NoSuchMethodError: net.minecraft.class_3283.method_14443(Lnet/minecraft/class_3285;)V
at chylex.respack.fabric.repository.NestedFolderPackFinder.register(NestedFolderPackFinder.java:16)
at chylex.respack.fabric.ResourcePackOrganizer.onInitializeClient(ResourcePackOrganizer.java:9)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointClient$$Lambda$2203/1946888484.accept(Unknown Source)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke0(EntrypointUtils.java:50)
... 11 more

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

-- Head --
Thread: Render thread
Stacktrace:
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke0(EntrypointUtils.java:53)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointUtils.invoke(EntrypointUtils.java:36)
at net.fabricmc.loader.entrypoint.minecraft.hooks.EntrypointClient.start(EntrypointClient.java:33)
at net.minecraft.class_310.(class_310.java:425)

-- Initialization --
Details:
Stacktrace:
at net.minecraft.client.main.Main.main(Main.java:177)
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.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:192)
at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:140)
at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:26)

-- System Details --
Details:
Minecraft Version: 1.16.1
Minecraft Version ID: 1.16.1
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: 879995432 bytes (839 MB) / 1476395008 bytes (1408 MB) up to 2147483648 bytes (2048 MB)
CPUs: 12
JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
Fabric Mods:
craftpresence: CraftPresence 1.6.6
fabric: Fabric API 0.13.1+build.370-1.16
fabric-api-base: Fabric API Base 0.1.3+12a8474c7c
fabric-biomes-v1: Fabric Biomes (v1) 0.2.7+059ea8667c
fabric-blockrenderlayer-v1: Fabric BlockRenderLayer Registration (v1) 1.1.4+c6a8ea897c
fabric-command-api-v1: Fabric Command API (v1) 1.0.8+5ce533987c
fabric-commands-v0: Fabric Commands (v0) 0.2.0+52d308367c
fabric-containers-v0: Fabric Containers (v0) 0.1.8+045df74f7c
fabric-content-registries-v0: Fabric Content Registries (v0) 0.1.9+059ea8667c
fabric-crash-report-info-v1: Fabric Crash Report Info (v1) 0.1.2+b7f9825d7c
fabric-dimensions-v1: fabric-dimensions-v1 1.0.0+a71b30537c
fabric-events-interaction-v0: Fabric Events Interaction (v0) 0.3.3+7066030f7c
fabric-events-lifecycle-v0: Fabric Events Lifecycle (v0) 0.1.3+0d474ec47c
fabric-item-groups-v0: Fabric Item Groups (v0) 0.2.0+438f96367c
fabric-key-binding-api-v1: Fabric Key Binding API (v1) 1.0.0+e16a97747c
fabric-keybindings-v0: Fabric Key Bindings (v0) 0.2.0+3fa9f7c57c
fabric-loot-tables-v1: Fabric Loot Tables (v1) 0.1.10+059ea8667c
fabric-mining-levels-v0: Fabric Mining Levels (v0) 0.1.2+b764ce997c
fabric-models-v0: Fabric Models (v0) 0.1.0+dfdb52d67c
fabric-networking-blockentity-v0: Fabric Networking Block Entity (v0) 0.2.5+b50ffc7b7c
fabric-networking-v0: Fabric Networking (v0) 0.1.10+e00ecb5f7c
fabric-object-builder-api-v1: Fabric Object Builder API (v1) 1.5.5+e00ecb5f7c
fabric-object-builders-v0: Fabric Object Builders (v0) 0.6.0+da175ad67c
fabric-particles-v1: fabric-particles-v1 0.2.1+0a6f2a707c
fabric-registry-sync-v0: Fabric Registry Sync (v0) 0.3.8+7dba2d6c7c
fabric-renderer-api-v1: Fabric Renderer API (v1) 0.2.13+eae12eb87c
fabric-renderer-indigo: Fabric Renderer - Indigo 0.3.1+059ea8667c
fabric-renderer-registries-v1: Fabric Renderer Registries (v1) 2.0.1+5a0f9a607c
fabric-rendering-data-attachment-v1: Fabric Rendering Data Attachment (v1) 0.1.3+b7f9825d7c
fabric-rendering-fluids-v1: Fabric Rendering Fluids (v1) 0.1.7+12a8474c7c
fabric-rendering-v0: Fabric Rendering (v0) 1.1.0+534104907c
fabric-rendering-v1: Fabric Rendering (v1) 1.1.2+346247d77c
fabric-resource-loader-v0: Fabric Resource Loader (v0) 0.2.5+059ea8667c
fabric-screen-handler-api-v1: Fabric Screen Handler API (v1) 1.0.1+f362c86e7c
fabric-tag-extensions-v0: Fabric Tag Extensions (v0) 0.2.5+5a6e8f4c7c
fabric-textures-v0: Fabric Textures (v0) 1.0.4+eae12eb87c
fabric-tool-attribute-api-v1: Fabric Tool Attribute API (v1) 1.1.4+5794386e7c
fabricloader: Fabric Loader 0.8.9+build.203
lithium: Lithium 0.5.0-rc1-SNAPSHOT
logical_zoom: Logical Zoom 0.0.4
minecraft: Minecraft 1.16.1
mm: Manningham Mills 2.0
optifabric: Optifabric 1.1.0-beta2
org_slf4j_slf4j-api: slf4j-api 1.7.30
org_slf4j_slf4j-simple: slf4j-simple 1.7.30
org_zeroturnaround_zt-zip: zt-zip 1.14
phosphor: Phosphor 0.6.0-SNAPSHOT
resourcepackorganizer: Resource Pack Organizer 1.1.0-Fabric
Launched Version: fabric-loader-0.8.9+build.203-1.16.1
Backend library: LWJGL version 3.2.2 build 10
Backend API: NO CONTEXT
GL Caps:
Using VBOs: Yes
Is Modded: Definitely; Client brand changed to 'fabric'
Type: Client (map_client.txt)
CPU:
OptiFine Version: OptiFine_1.16.1_HD_U_G2_pre2
OptiFine Build: 20200703-234202
Shaders: null
OpenGlVersion: null
OpenGlRenderer: null
OpenGlVendor: null
CpuCount: 0

No plans to update Fabric atm, 1.16 made things more complicated and it'd need more work than expected. I have updated Forge for the moment, so if anyone has the time to port all the changes I needed to make, PRs are welcome.