In my case I tested on Legacy Fabric 1.4.5, but the issue will arise on any version that doesn't include the mojang logging utils.
Failed to invoke the Minecraft main class:
java.lang.NoClassDefFoundError: com/mojang/logging/LogUtils
at io.github.gaming32.modloadingscreen.ModLoadingScreen.<clinit>(ModLoadingScreen.java:25)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:467)
at net.fabricmc.loader.impl.FabricLoaderImpl.setupLanguageAdapters(FabricLoaderImpl.java:400)
at net.fabricmc.loader.impl.FabricLoaderImpl.finishModLoading(FabricLoaderImpl.java:310)
at net.fabricmc.loader.impl.FabricLoaderImpl.freeze(FabricLoaderImpl.java:110)
at net.fabricmc.loader.impl.launch.knot.Knot.init(Knot.java:149)
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:68)
at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.multimc.onesix.OneSixLauncher.legacyLaunch(OneSixLauncher.java:149)
at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:244)
at org.multimc.EntryPoint.listen(EntryPoint.java:143)
at org.multimc.EntryPoint.main(EntryPoint.java:34)
Caused by: java.lang.ClassNotFoundException: com.mojang.logging.LogUtils
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226)
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:112)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
... 17 more
In my case I tested on Legacy Fabric 1.4.5, but the issue will arise on any version that doesn't include the mojang logging utils.