The INCOMPATIBLE- message described suddenly occured ...
Bitbucket Server 6.8.2 is runnung since January 2020
Bitbucket Server 7.5.0 ist running since August, 14, 2020
In may I've already raised the ticket :
https://getsupport.atlassian.com/servicedesk/customer/portal/24/SSP-43526
Can you confirm that it's only a documentaion issue and that the v3.2.3 is compatible with Bitbucket Server 6.8.2 and 7.5.0 ?