We are running with Splunk Cloud 126.96.36.199 version in our environment. And now we are planning to upgrade the same to 8.0. and above version.
So I have logged a ticket to Splunk Support for upgrading the core Splunk Cloud they said to review the Cloud Monitoring Console App installed in the Search head and then have navigated to Splunk Upgrade Dashboard.
Splunk App Compatibility Summary Forwarder Compatibility Forwarder Count by Status
Here in the Forwarder Count by Status i can see under Provisional some 10 client machines and in Upgrade Needed i can see around 20 client machines.
So when i viewed the list i came to know that most of the servers are Windows 2003 OS and they are running with Splunk Forwarder version of 6.2.15 and few of them are RHEL 5 (5.11) running with 6.5.1 Splunk Forwarder version.
So as of now teams are working to decommission this old servers but it might take few months but still I want to know If we upgrade the core Splunk Cloud to 8.0 and above will be the client machines running with OS (Win2k3 & RHEL 5 (5.11)) and Splunk Forwarder versions (6.2.15 & 6.5.1) are able to ingest logs into Splunk Cloud without any issues?
If its not possible to upgrade your 6.x instances, whilst not necessarily best practice, you may be able to use an Intermediary Forwarder running 7.3 to receive your 6.x traffic and send on to Splunk Cloud running 8.x