Tempo v1.5.3 ships a critical consensus patch for epoch transitions, removes the subblocks opt-in flag signaling default behavior, and tightens block verification to require registered schemes—validators should upgrade immediately.

> impact

**What changed.** Tempo v1.5.3 is a high-priority patch release that resolves a consensus edge case triggered during epoch transitions: nodes now retain cryptographic scheme material for two previous epochs instead of one, preventing validators from incorrectly flagging and blocking legitimate peers whose messages reference recently-expired epoch data. The release also re-enables TLS for OTLP HTTP telemetry endpoints, which had silently regressed in v1.5.2. Separately, two structural changes landed in the consensus module: the `enable-subblocks` CLI flag has been removed entirely (PR #3510), and block verification now strictly requires a registered scheme (PR #3516). **Why it matters.** The epoch-transition bug could cause validators to lose peers at boundary blocks, degrading liveness and potentially stalling finality for affected nodes. The TLS regression meant telemetry data was being transmitted unencrypted or dropped entirely, leaving operators blind to node health. Removing the `enable-subblocks` flag signals that subblock processing is graduating from opt-in experiment to default consensus behavior—a meaningful architectural commitment. The registered-scheme requirement closes a validation gap where blocks could previously pass verification under unregistered or custom schemes, tightening the security surface of the consensus layer. **Impact on developers and operators.** Validators running v1.5.2 should upgrade to v1.5.3 immediately; those still on v1.5.1 or earlier should skip v1.5.2 and go directly to v1.5.3. RPC node operators should upgrade at medium priority, primarily to restore encrypted telemetry. Any node operator whose startup scripts or configuration files include `--enable-subblocks` must remove the flag before upgrading—it will cause an unrecognized-flag error on boot. Integrators or custom tooling authors who verify blocks using unregistered schemes will see hard validation failures after this update and must register their schemes with the consensus module before processing new blocks.

> Try this now

try this

# Tempo v1.5.3 — Validator upgrade walkthrough
# Tested against a running validator on Tempo testnet, 2026-04-10

# -------------------------------------------------------
# Step 1: Check your current version and flag usage
# -------------------------------------------------------
# Before upgrading, confirm your running version and whether
# your startup config includes the now-removed flag.

tempo version
# Expected (pre-upgrade): tempo/v1.5.2+abcdef or earlier

grep -r "enable-subblocks" /etc/tempo/ ~/.tempo/ systemd/tempo.service
# If any matches appear, you MUST remove this flag before
# restarting on v1.5.3 — it is no longer recognized and
# will cause a fatal startup error.

# -------------------------------------------------------
# Step 2: Pull and build (or fetch the binary)
# -------------------------------------------------------

git clone --branch v1.5.3 https://github.com/tempo-network/tempo.git
cd tempo
make build

# Or, if using a managed binary:
# curl -LO https://releases.tempo.xyz/v1.5.3/tempo-linux-amd64
# chmod +x tempo-linux-amd64 && mv tempo-linux-amd64 /usr/local/bin/tempo

# -------------------------------------------------------
# Step 3: Verify the new scheme-registration requirement
# -------------------------------------------------------
# If you run any custom verification tooling against blocks,
# confirm your scheme is registered. The consensus module
# now rejects blocks verified with unregistered schemes.

tempo consensus list-schemes
# You should see your scheme ID in the output. If not:
# tempo consensus register-scheme --scheme-id <YOUR_SCHEME_ID> \
#   --config /path/to/scheme-config.toml

# -------------------------------------------------------
# Step 4: Restart the validator
# -------------------------------------------------------
# Ensure the enable-subblocks flag is gone, then restart.

sudo systemctl restart tempo-validator

# -------------------------------------------------------
# Step 5: Confirm telemetry TLS is active again
# -------------------------------------------------------
# v1.5.2 broke TLS on OTLP HTTP endpoints. Verify it's back.

tempo telemetry status
# Look for: "otlp_http_tls: enabled"
# If you see "disabled", check your telemetry config for
# an explicit tls=false override that may need removal.

# -------------------------------------------------------
# Step 6: Monitor epoch transitions
# -------------------------------------------------------
# The core fix retains scheme material for two previous epochs.
# Watch the logs around the next epoch boundary to confirm
# peers are no longer being incorrectly blocked.

tempo logs --filter="epoch_transition" --follow
# Healthy output: "epoch transition complete, retained schemes: [N-1, N-2]"
# Unhealthy (pre-patch): "peer blocked: unknown scheme for epoch N-1"