Issues with MySQL upgrade from PXC 5.7 to PXC 8.0

I have setup a Percona XtraDB Cluster in 5.7 version and trying to upgrade to 8.0. I was trying to upgrade one node to 8.0 by swapping the Binaries from 5.7 to 8.0 and also XtraBackup from 2.4 to 8.0.

I tried to restart the node using 8.0 binaries and the node started up and from the logs I see the upgrade was successfully as well. But when I login to upgraded node, show global variables and show global status does not return any result set even though if I manually select the variable using select @@variaable_name I get those values. Other than that the node looks operational and Galera replication is also working fine. 

However, when I run xtrabackup to backup the DB's on the upgraded node, I get a error shown below. Because of this I am not able to upgrade the full cluster as when the newly upgraded node becomes the DONOR it fails to upgrade the other nodes and keep up with the cluster.

"xtrabackup got signal 11 ; this could be because you hit a bug or data is corrupted. this error can also be caused by malfunctioning hardware. attempting to collect some information that could help diagnose the problem"

This is impacting production and am stuck with this since almost a week.