Hi everyone,  I experienced the same error. After inspecting also the logs of nifi-registry, I found the error  2023-09-04 16:18:10,346 ERROR [NiFi Registry Web Server-17] o.a.n.r.web.mapper.ThrowableMapper An unexpected error has occurred: org.apache.nifi.registry.flow.FlowPersistenceException: Git directory /data/nifi01/nifi-registry-1.18.0/../nifiregistry_git is not clean or has uncommitted changes, resolve those changes first to save flow contents.. Returning Internal Server Error response. org.apache.nifi.registry.flow.FlowPersistenceException: Git directory /data/nifi01/nifi-registry-1.18.0/../nifiregistry_git is not clean or has uncommitted changes, resolve those changes first to save flow contents.   I changed to the path noted in the error message, changed to the user, which executes nifi-registry and checked the git repository status: git status Several files were modified and the git directory clearly was not "clean". I just committed and pushed everything (I had to set the git user name to make a successful commit).  I don't know, why this all happend. But for now, its fixed.  ... View more

@MattWho In my test the truststore did contain just a single certificate, the public certificate of the authorized user (not private key). However this did not work, the TLS handshake did fail. In the end I did solve my problem like you suggested, with RouteOnAttribute on "http.subject.dn". It would be nice to have a processor for accessing AD to compare if the selected dn is member of some AD-group. ... View more