dex2jar has illegal reflective accesses and subsequently fails

[vguttmann]

This happens on a brand new Ubuntu 20.04.1 LTS installation which is using WSL1 (I don't think that's the issue, but I mention it regardless). After installation, I installed default-jre and default-jdk via apt, and tried to run the script. I have no idea how to fix these errors, can someone help me out here?

Here is the complete output:

guttmann@Guttmann-Lenovo:~/AndroidDecompiler$ bash decompileAPK.sh DexcomG6US-015151112010.apk
Decompiling APK file DexcomG6US-015151112010.apk
Results will be put in ./output

Cleaning up the output directories
Extracting JAR file from APK
dex2jar DexcomG6US-015151112010.apk -> ./output/output.jar
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.googlecode.dex2jar.reader.ZipInputStreamHack (file:/home/guttmann/AndroidDecompiler/dex2jar/lib/dex-reader-1.15.jar) to field java.util.zip.ZipInputStream.flag
WARNING: Please consider reporting this to the maintainers of com.googlecode.dex2jar.reader.ZipInputStreamHack
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
com.googlecode.dex2jar.DexException: not support version.
        at com.googlecode.dex2jar.reader.DexFileReader.<init>(DexFileReader.java:166)
        at com.googlecode.dex2jar.reader.DexFileReader.<init>(DexFileReader.java:229)
        at com.googlecode.dex2jar.reader.DexFileReader.<init>(DexFileReader.java:240)
        at com.googlecode.dex2jar.tools.Dex2jarCmd.doCommandLine(Dex2jarCmd.java:104)
        at com.googlecode.dex2jar.tools.BaseCmd.doMain(BaseCmd.java:174)
        at com.googlecode.dex2jar.tools.Dex2jarCmd.main(Dex2jarCmd.java:34)
Decompiling JAR for Java files
java.io.FileNotFoundException: ./output/output.jar (No such file or directory)
        at java.base/java.io.FileInputStream.open0(Native Method)
        at java.base/java.io.FileInputStream.open(FileInputStream.java:219)
        at java.base/java.io.FileInputStream.<init>(FileInputStream.java:157)
        at java.base/java.io.FileInputStream.<init>(FileInputStream.java:112)
        at jd.core.Decompiler.decompile(Decompiler.java:28)
        at jd.core.Decompiler.decompileToDir(Decompiler.java:56)
        at jd.core.Main.main(Main.java:16)
rm: cannot remove './output/output.jar': No such file or directory
Extracting resources from APK file
I: Baksmaling...
Exception in thread "main" java.lang.RuntimeException: bad magic value: 64 65 78 0a 30 33 37 00
        at org.jf.dexlib.DexFile.<init>(DexFile.java:377)
        at org.jf.dexlib.DexFile.<init>(DexFile.java:267)
        at brut.androlib.src.SmaliDecoder.decode(SmaliDecoder.java:49)
        at brut.androlib.src.SmaliDecoder.decode(SmaliDecoder.java:34)
        at brut.androlib.Androlib.decodeSourcesSmali(Androlib.java:74)
        at brut.androlib.ApkDecoder.decode(ApkDecoder.java:89)
        at brut.apktool.Main.cmdDecode(Main.java:146)
        at brut.apktool.Main.main(Main.java:77)
rm: cannot remove './output/res-output/apktool.yml': No such file or directory
mv: cannot stat './output/res-output/*': No such file or directory
guttmann@Guttmann-Lenovo:~/AndroidDecompiler$