having problem converting .ab file to .tar

Question

I extracted the package of the app Dafit successfully with ADB. using this command,

adb backup -apk com.crrepa.band.dafit

with that command I got a file named backup.ab

Now I'm using abe.jar to convert that .ab into .tar . I pasted bacup.ab and abe.jar into same folder and wrote this command in CMD

"C:\Program Files (x86)\Java\jre1.8.0_321\bin\java.exe" -jar abe.jar unpack backup.ab backup.tar

when I press enter, this result is shown...

49% 1024 bytes written to backup.tar.

I get the backup.tar file in the folder, but when I try to open it, it gives this error..

Is there any problem with the process..? What should I do to open that .tar file..?