$ java -jar ./Minecraft.jar
Bootstrap (v5)
Current time is Aug 17, 2021, 3:05:26 AM
System.getProperty('os.name') == 'Linux'
System.getProperty('os.version') == '5.11.0-25-generic'
System.getProperty('os.arch') == 'amd64'
System.getProperty('java.version') == '16.0.1'
System.getProperty('java.vendor') == 'Private Build'
System.getProperty('sun.arch.data.model') == '64'

Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma
Got reply in: 859ms
Downloaded 1076.7kb in 1s at 871.1kb/s
Renaming /home/user/.minecraft/launcher.pack.lzma.new to /home/user/.minecraft/launcher.pack.lzma
Renamed successfully.
Reversing LZMA on /home/user/.minecraft/launcher.pack.lzma to /home/user/.minecraft/launcher.pack
Unpacking /home/user/.minecraft/launcher.pack to /home/user/.minecraft/launcher.jar
FATAL ERROR: java.lang.NoClassDefFoundError: java/util/jar/Pack200
at net.minecraft.bootstrap.Bootstrap.unpack(Bootstrap.java:157)
at net.minecraft.bootstrap.Bootstrap.execute(Bootstrap.java:123)
at net.minecraft.bootstrap.Bootstrap.main(Bootstrap.java:381)
Caused by: java.lang.ClassNotFoundException: java.util.jar.Pack200
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
... 3 more

Please fix the error and restart.