tar: short read

I suspect that your tarfile is corrupted or truncated.

The header of a tarfile contains a size field that contains the length of the file.¹ If the actual file is shorter than the header says it should be, tar will try to read past the filesystem end of file and get back a read shorter than it expected, thus generating the message you see.

¹ This feature dates to when tar was used primarily for Tape ARchiving where you could only know the length of a "file" by reading until you hit an EOF marker on the tape. It was retained for backwards compatibility and also provides a nice (if kinda cheap) check on header and file consistency.

Usually this message appears if the tar archive is incomplete. If you run tar tvf ./VM_DECOMPTEST.tar it will check the tar file for inconsistencies.