According to proposal 303, we recommend some protocol versions every time an LTS release is no longer supported: https://gitweb.torproject.org/torspec.git/tree/proposals/303-protover-removal-policy.txt#n18 0.2.9.8 supported these protocol versions: https://gitweb.torproject.org/tor.git/tree/src/or/protover.c?h=tor-0.2.9.8#n283 When 0.2.9 is no longer supported, the earliest stable LTS will be 0.3.5.7, which supports these protocol versions: https://gitweb.torproject.org/tor.git/tree/src/core/or/protover.c?h=tor-0.3.5.7#n379 Therefore, we should recommend these protocol versions for clients and relays: Cons=2 Desc=2 DirCache=2 * HSDir=2 * HSIntro=4 * HSRend=2 Link=5 * LinkAuth=3 * Microdesc=2 Relay=2 The starred protovers are not supported by 0.2.9, so it will warn on bootstrap / consensus download. We can make that change in master here: https://gitweb.torproject.org/tor.git/tree/src/feature/dirauth/dirvote.c#n4630 The required protocols must stay the same, I'll open another ticket for them.