Cluster creation goes wrong with couchbase 7 on Buster

Hi ,
when I set up a new couchbase server on Debian Buster, I can’t complete the cluster setup via http .

I receive a generic error at the end :

’ Unexpected server error, request logged.’

If I also try to set up a new cluster via cli command (), I receive the following error:
‘ERROR: Internal server error, please retry your request’
I use a similar command syntax:

couchbase-cli cluster-init -c 10.x.y.z --cluster-username username  --cluster-password userpassword  --services data,index  --cluster-ramsize 8192 --cluster-index-ramsize 2048

The problem only appears with couchbase-server 7.x releases . The cluster setup works out well with the 6.6.x releases on the same servers .