Splunk DBConnect 3.4.0: dbxquery is not running

[mlevsh]

Hi,

We installed Splunk DBConnect 3.4.0 on our Search Head Cluster

We configured identity and connections successfully and were able to get results to |dbxquery command against the connections

Recently we upgraded to Splunk Enterprise to version 8.0.6 and cannot run |dbxquery anymore

We tried to re-save Identity and Connections again, but cannot save it on one search head out of 3, it triggers the error: Database connection "connection_name" is invalid . !200051!

While it is possible to save the same connection on other 2 servers -  |dbxquery doesn't work anywhere 

Any ideas are appreciated

Thanks!