cbindex failed to list index

Steps to reproduce:

• Install Couchbase server 5.0.0 on 2 centos servers (224 and 225).
• Initial nodes with services:kv,index,n1ql,fts and kv
• Create default bucket.
• Create 2 indexes.
• Install Couchbase server 6.5.0-4169 on other 2 centos 7.6 servers (226 and 227).
• Swap rebalance (add 226, 227 and remove 224,225 out of cluser) to upgrade 5.0.0 cluster to 6.5.0-4169.
• Run cbdindex to list index in new upgrade cluster, failed to list with error:
  ERROR - 2019/09/03 10:19:25 revrpc: Got error (EOF) and will retry in 1s

This error in cbindex made all tests with verifying indexes after upgrade failed.