The removal of the tevent ports backend was incomplete.
This bug was referenced in samba master:
Created attachment 17746 [details]
Patches for v4-18-test (ldb version 2.7.1)
Re-assigning to Jule for inclusion in 4.18.rcNext.
Pushed to autobuild-v4-18-test.
This bug was referenced in samba v4-18-test:
ldb version 2.7.1 and tevent 0.14.1 are released
This bug was referenced in samba v4-18-stable (Release samba-4.18.0rc3):