ERR_MIXED_MODE in eventing function resume


I have a 3 node cluster with couchbase 6.6.2 enterprise edition. All three nodes have the eventing service enabled an run an eventing function.
Now I want to upgrade my cluster to version 7.1.1, I thought I can simply upgrade one node to version 7.1.1 so I removed node 3, upgraded it to 7.1.1 and joined it to the cluster, so far all good.
I noticed that my eventing function was stopped after I added node 3. I tried to resume it and got this error message:

resume failed: {“name”:“ERR_MIXED_MODE”,“code”:46,“description”:“Life-cycle operations except delete and undeploy are not allowed in a mixed mode cluster”}

This leads me to the conclusion that a rolling update from 6.6.2 to 7.1.1 is not possible with “running” functions. I have to upgrade all nodes to 7.1.1 then I can resume my function, right?

Faris Ahmed