This article explains the reason for the error: /usr/bin/tar was not successful error to occur when a commit operation is performed on Routing Engine 0 (re0) on MX Series routers, and suggests a way to resolve the error.

When a commit operation is performed on NG-RE, the following error is output on re0.

{MASTER}[edit]
labroot@jtac-mx960-r2019-re0# commit check
re0:
configuration check succeeds
re1:
error: /usr/bin/tar was not successful

The reason is seen to be the usage of tar to push scripts across the RE while performing the commit operation.

Note: Although the error is output on re0, the fault with processing tar files is in re1.

To resolve the error, the entire RE must be formatted with a USB image, such as  junos-vmhost-install-usb-mx-xxx.tgz . Re-installation with  junos-vmhost-install-mx-x86-64-xxx.tgz will not work.