I recently updated my java version to jdk 16.0.1 from jre8u291 for some reason. It seemed that unforged client works well with the jdk, but forged client failed to start.
Here is the log:(HMCL dev-3.3.184)
Command: "C:\\Program Files\\Java\\jdk-16.0.1\\bin\\java.exe" -Dminecraft.client.jar=.minecraft\versions\1.16.5\1.16.5.jar -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M -XX:-UseAdaptiveSizePolicy -XX:-OmitStackTraceInFastThrow -Xmn128m -Xmx10240m -Dfml.ignoreInvalidMinecraftCertificates=true -Dfml.ignorePatchDiscrepancies=true -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Djava.library.path=D:\MC\.minecraft\versions\1.16.5-forge-36.1.16\natives -Dminecraft.launcher.brand=HMCL -Dminecraft.launcher.version=3.3.184 -cp D:\MC\.minecraft\libraries\net\minecraftforge\forge\1.16.5-36.1.16\forge-1.16.5-36.1.16.jar;D:\MC\.minecraft\libraries\org\ow2\asm\asm\9.0\asm-9.0.jar;D:\MC\.minecraft\libraries\org\ow2\asm\asm-commons\9.0\asm-commons-9.0.jar;D:\MC\.minecraft\libraries\org\ow2\asm\asm-tree\9.0\asm-tree-9.0.jar;D:\MC\.minecraft\libraries\org\ow2\asm\asm-util\9.0\asm-util-9.0.jar;D:\MC\.minecraft\libraries\org\ow2\asm\asm-analysis\9.0\asm-analysis-9.0.jar;D:\MC\.minecraft\libraries\cpw\mods\modlauncher\8.0.9\modlauncher-8.0.9.jar;D:\MC\.minecraft\libraries\cpw\mods\grossjava9hacks\1.3.3\grossjava9hacks-1.3.3.jar;D:\MC\.minecraft\libraries\net\minecraftforge\accesstransformers\3.0.1\accesstransformers-3.0.1.jar;D:\MC\.minecraft\libraries\org\antlr\antlr4-runtime\4.9.1\antlr4-runtime-4.9.1.jar;D:\MC\.minecraft\libraries\net\minecraftforge\eventbus\4.0.0\eventbus-4.0.0.jar;D:\MC\.minecraft\libraries\net\minecraftforge\forgespi\3.2.0\forgespi-3.2.0.jar;D:\MC\.minecraft\libraries\net\minecraftforge\coremods\4.0.6\coremods-4.0.6.jar;D:\MC\.minecraft\libraries\net\minecraftforge\unsafe\0.2.0\unsafe-0.2.0.jar;D:\MC\.minecraft\libraries\com\electronwill\night-config\core\3.6.3\core-3.6.3.jar;D:\MC\.minecraft\libraries\com\electronwill\night-config\toml\3.6.3\toml-3.6.3.jar;D:\MC\.minecraft\libraries\org\jline\jline\3.12.1\jline-3.12.1.jar;D:\MC\.minecraft\libraries\org\apache\maven\maven-artifact\3.6.3\maven-artifact-3.6.3.jar;D:\MC\.minecraft\libraries\net\jodah\typetools\0.8.3\typetools-0.8.3.jar;D:\MC\.minecraft\libraries\org\apache\logging\log4j\log4j-api\2.11.2\log4j-api-2.11.2.jar;D:\MC\.minecraft\libraries\org\apache\logging\log4j\log4j-core\2.11.2\log4j-core-2.11.2.jar;D:\MC\.minecraft\libraries\net\minecrell\terminalconsoleappender\1.2.0\terminalconsoleappender-1.2.0.jar;D:\MC\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\5.0.4\jopt-simple-5.0.4.jar;D:\MC\.minecraft\libraries\org\spongepowered\mixin\0.8.2\mixin-0.8.2.jar;D:\MC\.minecraft\libraries\net\minecraftforge\nashorn-core-compat\15.1.1.1\nashorn-core-compat-15.1.1.1.jar;D:\MC\.minecraft\libraries\com\mojang\patchy\1.1\patchy-1.1.jar;D:\MC\.minecraft\libraries\oshi-project\oshi-core\1.1\oshi-core-1.1.jar;D:\MC\.minecraft\libraries\net\java\dev\jna\jna\4.4.0\jna-4.4.0.jar;D:\MC\.minecraft\libraries\net\java\dev\jna\platform\3.4.0\platform-3.4.0.jar;D:\MC\.minecraft\libraries\com\ibm\icu\icu4j\66.1\icu4j-66.1.jar;D:\MC\.minecraft\libraries\com\mojang\javabridge\1.0.22\javabridge-1.0.22.jar;D:\MC\.minecraft\libraries\io\netty\netty-all\4.1.25.Final\netty-all-4.1.25.Final.jar;D:\MC\.minecraft\libraries\com\google\guava\guava\21.0\guava-21.0.jar;D:\MC\.minecraft\libraries\org\apache\commons\commons-lang3\3.5\commons-lang3-3.5.jar;D:\MC\.minecraft\libraries\commons-io\commons-io\2.5\commons-io-2.5.jar;D:\MC\.minecraft\libraries\commons-codec\commons-codec\1.10\commons-codec-1.10.jar;D:\MC\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;D:\MC\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;D:\MC\.minecraft\libraries\com\mojang\brigadier\1.0.17\brigadier-1.0.17.jar;D:\MC\.minecraft\libraries\com\mojang\datafixerupper\4.0.26\datafixerupper-4.0.26.jar;D:\MC\.minecraft\libraries\com\google\code\gson\gson\2.8.0\gson-2.8.0.jar;D:\MC\.minecraft\libraries\com\mojang\authlib\2.1.28\authlib-2.1.28.jar;D:\MC\.minecraft\libraries\org\apache\commons\commons-compress\1.8.1\commons-compress-1.8.1.jar;D:\MC\.minecraft\libraries\org\apache\httpcomponents\httpclient\4.3.3\httpclient-4.3.3.jar;D:\MC\.minecraft\libraries\commons-logging\commons-logging\1.1.3\commons-logging-1.1.3.jar;D:\MC\.minecraft\libraries\org\apache\httpcomponents\httpcore\4.3.2\httpcore-4.3.2.jar;D:\MC\.minecraft\libraries\it\unimi\dsi\fastutil\8.2.1\fastutil-8.2.1.jar;D:\MC\.minecraft\libraries\org\lwjgl\lwjgl\3.2.2\lwjgl-3.2.2.jar;D:\MC\.minecraft\libraries\org\lwjgl\lwjgl-jemalloc\3.2.2\lwjgl-jemalloc-3.2.2.jar;D:\MC\.minecraft\libraries\org\lwjgl\lwjgl-openal\3.2.2\lwjgl-openal-3.2.2.jar;D:\MC\.minecraft\libraries\org\lwjgl\lwjgl-opengl\3.2.2\lwjgl-opengl-3.2.2.jar;D:\MC\.minecraft\libraries\org\lwjgl\lwjgl-glfw\3.2.2\lwjgl-glfw-3.2.2.jar;D:\MC\.minecraft\libraries\org\lwjgl\lwjgl-stb\3.2.2\lwjgl-stb-3.2.2.jar;D:\MC\.minecraft\libraries\org\lwjgl\lwjgl-tinyfd\3.2.2\lwjgl-tinyfd-3.2.2.jar;D:\MC\.minecraft\libraries\com\mojang\text2speech\1.11.3\text2speech-1.11.3.jar;D:\MC\.minecraft\versions\1.16.5\1.16.5.jar cpw.mods.modlauncher.Launcher --username Tiger__Shark --version "HMCL 3.3.184" --gameDir D:\MC\.minecraft\versions\1.16.5-forge-36.1.16 --assetsDir D:\MC\.minecraft\assets --assetIndex 1.16 --uuid d5e3b40ce17b4dadb33bb264e2b076d4 --accessToken eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIyZjM0Y2VmODMyZjBlY2Q4MmMyOTczMDU3NGUyNmViZSIsInlnZ3QiOiI1M2M0NTdkZTVmYmE0NTRhOGUyMWFjZWQzY2MyNzdiNSIsInNwciI6ImQ1ZTNiNDBjZTE3YjRkYWRiMzNiYjI2NGUyYjA3NmQ0IiwiaXNzIjoiWWdnZHJhc2lsLUF1dGgiLCJleHAiOjE2MjEyMjg0NTQsImlhdCI6MTYyMTA1NTY1NH0.KQzr-VN-73lz6zq0Olz703kpKjGO1l-xfgs26_3Enaw --userType mojang --versionType "HMCL 3.3.184" --width 854 --height 480 --launchTarget fmlclient --fml.forgeVersion 36.1.16 --fml.mcVersion 1.16.5 --fml.forgeGroup net.minecraftforge --fml.mcpVersion 20210115.111550
2021-05-15 13:14:26,900 main WARN Advanced terminal features are not available in this environment
[13:14:27] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--username, <player>, --version, HMCL 3.3.184, --gameDir, D:\MC\.minecraft\versions\1.16.5-forge-36.1.16, --assetsDir, D:\MC\.minecraft\assets, --assetIndex, 1.16, --uuid, <uuid>, --accessToken, ????????, --userType, mojang, --versionType, HMCL 3.3.184, --width, 854, --height, 480, --launchTarget, fmlclient, --fml.forgeVersion, 36.1.16, --fml.mcVersion, 1.16.5, --fml.forgeGroup, net.minecraftforge, --fml.mcpVersion, 20210115.111550]
[13:14:27] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 8.0.9+86+master.3cf110c starting: java version 16.0.1 by Oracle Corporation
Exception in thread "main" java.lang.IllegalAccessError: class cpw.mods.modlauncher.SecureJarHandler (in unnamed module @0x7ba18f1b) cannot access class sun.security.util.ManifestEntryVerifier (in module java.base) because module java.base does not export sun.security.util to unnamed module @0x7ba18f1b
at cpw.mods.modlauncher.SecureJarHandler.lambda$static$1(SecureJarHandler.java:41)
at cpw.mods.modlauncher.api.LamdbaExceptionUtils.uncheck(LamdbaExceptionUtils.java:95)
at cpw.mods.modlauncher.SecureJarHandler.<clinit>(SecureJarHandler.java:41)
at cpw.mods.modlauncher.Launcher.lambda$new$6(Launcher.java:55)
at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1708)
at cpw.mods.modlauncher.api.TypesafeMap.computeIfAbsent(TypesafeMap.java:52)
at cpw.mods.modlauncher.api.TypesafeMap.computeIfAbsent(TypesafeMap.java:47)
at cpw.mods.modlauncher.Environment.computePropertyIfAbsent(Environment.java:62)
at cpw.mods.modlauncher.Launcher.<init>(Launcher.java:55)
at cpw.mods.modlauncher.Launcher.main(Launcher.java:66)