diff --git a/zebra-chain/src/block/arbitrary.rs b/zebra-chain/src/block/arbitrary.rs
index 5a39afa2e..02cfca435 100644
--- a/zebra-chain/src/block/arbitrary.rs
+++ b/zebra-chain/src/block/arbitrary.rs
@@ -260,8 +260,9 @@ impl Default for LedgerState {
         let default_override = LedgerStateOverride::default();
 
         let most_recent_nu = NetworkUpgrade::current(&default_network, Height::MAX);
-        let most_recent_activation_height =
-            most_recent_nu.activation_height(&default_network).unwrap();
+        let most_recent_activation_height = most_recent_nu
+            .activation_height(&default_network)
+            .expect("should have an activation height in default networks");
 
         LedgerState {
             height: most_recent_activation_height,
@@ -467,8 +468,10 @@ impl Block {
                     let current_height = block.coinbase_height().unwrap();
                     let heartwood_height = NetworkUpgrade::Heartwood
                         .activation_height(&current.network)
-                        .unwrap();
-                    let nu5_height = NetworkUpgrade::Nu5.activation_height(&current.network);
+                        .expect("should have an activation height in default networks");
+                    let nu5_height = NetworkUpgrade::Nu5
+                        .activation_height(&current.network)
+                        .expect("should have an activation height in default networks");
 
                     match current_height.cmp(&heartwood_height) {
                         std::cmp::Ordering::Less => {
@@ -491,7 +494,7 @@ impl Block {
                                 Some(tree) => tree.hash().unwrap_or_else(|| [0u8; 32].into()),
                                 None => [0u8; 32].into(),
                             };
-                            if nu5_height.is_some() && current_height >= nu5_height.unwrap() {
+                            if current_height >= nu5_height {
                                 // From zebra-state/src/service/check.rs
                                 let auth_data_root = block.auth_data_root();
                                 let hash_block_commitments =
@@ -696,7 +699,11 @@ impl Arbitrary for Commitment {
     fn arbitrary_with(_args: ()) -> Self::Strategy {
         (any::<[u8; 32]>(), any::<Network>(), any::<Height>())
             .prop_map(|(commitment_bytes, network, block_height)| {
-                if block_height == Heartwood.activation_height(&network).unwrap() {
+                if block_height
+                    == Heartwood
+                        .activation_height(&network)
+                        .expect("should have an activation height in default networks")
+                {
                     Commitment::ChainHistoryActivationReserved
                 } else {
                     Commitment::from_bytes(commitment_bytes, &network, block_height)
diff --git a/zebra-chain/src/block/tests/vectors.rs b/zebra-chain/src/block/tests/vectors.rs
index 5ff19ca10..7f56b263a 100644
--- a/zebra-chain/src/block/tests/vectors.rs
+++ b/zebra-chain/src/block/tests/vectors.rs
@@ -223,7 +223,7 @@ fn block_test_vectors_height(network: Network) {
         if height
             >= Sapling
                 .activation_height(&network)
-                .expect("sapling activation height is set")
+                .expect("sapling activation height is set on default network")
                 .0
         {
             assert!(
diff --git a/zebra-chain/src/chain_tip/tests/prop.rs b/zebra-chain/src/chain_tip/tests/prop.rs
index 3b5fff99f..612bad1cd 100644
--- a/zebra-chain/src/chain_tip/tests/prop.rs
+++ b/zebra-chain/src/chain_tip/tests/prop.rs
@@ -25,7 +25,7 @@ proptest! {
         let (chain_tip, mock_chain_tip_sender) = MockChainTip::new();
         let blossom_activation_height = NetworkUpgrade::Blossom
             .activation_height(&network)
-            .expect("Blossom activation height is missing");
+            .expect("Blossom activation height is missing on default network");
 
         block_heights.sort();
         let current_height = block_heights[0];
diff --git a/zebra-chain/src/history_tree.rs b/zebra-chain/src/history_tree.rs
index d3a45f15f..59dcb13a6 100644
--- a/zebra-chain/src/history_tree.rs
+++ b/zebra-chain/src/history_tree.rs
@@ -428,9 +428,11 @@ impl HistoryTree {
         sapling_root: &sapling::tree::Root,
         orchard_root: &orchard::tree::Root,
     ) -> Result<Self, HistoryTreeError> {
-        let heartwood_height = NetworkUpgrade::Heartwood
-            .activation_height(network)
-            .expect("Heartwood height is known");
+        let Some(heartwood_height) = NetworkUpgrade::Heartwood.activation_height(network) else {
+            // Return early if there is no Heartwood activation height.
+            return Ok(HistoryTree(None));
+        };
+
         match block
             .coinbase_height()
             .expect("must have height")
diff --git a/zebra-chain/src/history_tree/tests/vectors.rs b/zebra-chain/src/history_tree/tests/vectors.rs
index e65da99b6..a02244109 100644
--- a/zebra-chain/src/history_tree/tests/vectors.rs
+++ b/zebra-chain/src/history_tree/tests/vectors.rs
@@ -35,7 +35,10 @@ fn push_and_prune_for_network_upgrade(
 ) -> Result<()> {
     let (blocks, sapling_roots) = network.block_sapling_roots_map();
 
-    let height = network_upgrade.activation_height(&network).unwrap().0;
+    let height = network_upgrade
+        .activation_height(&network)
+        .expect("network upgrade activation height is missing on default network")
+        .0;
 
     // Load first block (activation block of the given network upgrade)
     let first_block = Arc::new(
@@ -118,7 +121,10 @@ fn upgrade() -> Result<()> {
 fn upgrade_for_network_upgrade(network: Network, network_upgrade: NetworkUpgrade) -> Result<()> {
     let (blocks, sapling_roots) = network.block_sapling_roots_map();
 
-    let height = network_upgrade.activation_height(&network).unwrap().0;
+    let height = network_upgrade
+        .activation_height(&network)
+        .expect("network upgrade activation height is missing on default network")
+        .0;
 
     // Load previous block (the block before the activation block of the given network upgrade)
     let block_prev = Arc::new(
diff --git a/zebra-chain/src/parameters/network.rs b/zebra-chain/src/parameters/network.rs
index 47fd41e74..6ef607663 100644
--- a/zebra-chain/src/parameters/network.rs
+++ b/zebra-chain/src/parameters/network.rs
@@ -267,6 +267,12 @@ impl Network {
         //
         // See the `ZIP_212_GRACE_PERIOD_DURATION` documentation for more information.
 
+        // TODO:
+        // - Support constructing pre-Canopy coinbase tx and block templates and return `Height::MAX` instead of panicking
+        //   when Canopy activation height is `None` (#8434)
+        // - Add semantic block validation during the ZIP-212 grace period and update this method to return the lesser of
+        //   `canopy_activation + ZIP_212_GRACE_PERIOD_DURATION` or the NU5 activation height. (#8430)
+
         let canopy_activation = NetworkUpgrade::Canopy
             .activation_height(self)
             .expect("Canopy activation height must be present for both networks");
@@ -296,10 +302,8 @@ impl Network {
     }
 
     /// Returns the Sapling activation height for this network.
-    pub fn sapling_activation_height(&self) -> Height {
-        super::NetworkUpgrade::Sapling
-            .activation_height(self)
-            .expect("Sapling activation height needs to be set")
+    pub fn sapling_activation_height(&self) -> Option<Height> {
+        super::NetworkUpgrade::Sapling.activation_height(self)
     }
 }
 
diff --git a/zebra-chain/src/parameters/network/tests/prop.rs b/zebra-chain/src/parameters/network/tests/prop.rs
index c2b1e31e0..1aad87547 100644
--- a/zebra-chain/src/parameters/network/tests/prop.rs
+++ b/zebra-chain/src/parameters/network/tests/prop.rs
@@ -19,7 +19,7 @@ proptest! {
 
         let canopy_activation = NetworkUpgrade::Canopy
             .activation_height(&network)
-            .expect("Canopy activation height is set");
+            .expect("Canopy activation height is set on default networks");
 
         let grace_period_end_height = (canopy_activation + ZIP_212_GRACE_PERIOD_DURATION)
             .expect("ZIP-212 grace period ends in a valid block height");
diff --git a/zebra-chain/src/parameters/network/tests/vectors.rs b/zebra-chain/src/parameters/network/tests/vectors.rs
index e54fa4d7c..dd1e51b7d 100644
--- a/zebra-chain/src/parameters/network/tests/vectors.rs
+++ b/zebra-chain/src/parameters/network/tests/vectors.rs
@@ -112,7 +112,7 @@ fn activates_network_upgrades_correctly() {
 
     let genesis_activation_height = NetworkUpgrade::Genesis
         .activation_height(&network)
-        .expect("must return an activation height");
+        .expect("must always return an activation height for Genesis network upgrade");
 
     assert_eq!(
         genesis_activation_height,
@@ -123,7 +123,7 @@ fn activates_network_upgrades_correctly() {
     for nu in NETWORK_UPGRADES_IN_ORDER.into_iter().skip(1) {
         let activation_height = nu
             .activation_height(&network)
-            .expect("must return an activation height");
+            .expect("must return an activation height for all network upgrades when there's an NU5 activation height");
 
         assert_eq!(
             activation_height, Height(expected_activation_height),
diff --git a/zebra-chain/src/parameters/network_upgrade.rs b/zebra-chain/src/parameters/network_upgrade.rs
index de546e3b4..4297eb764 100644
--- a/zebra-chain/src/parameters/network_upgrade.rs
+++ b/zebra-chain/src/parameters/network_upgrade.rs
@@ -402,14 +402,10 @@ impl NetworkUpgrade {
             ),
         ]
         .into_iter()
-        .map(move |(upgrade, spacing_seconds)| {
-            let activation_height = upgrade
-                .activation_height(network)
-                .expect("missing activation height for target spacing change");
-
+        .filter_map(move |(upgrade, spacing_seconds)| {
+            let activation_height = upgrade.activation_height(network)?;
             let target_spacing = Duration::seconds(spacing_seconds);
-
-            (activation_height, target_spacing)
+            Some((activation_height, target_spacing))
         })
     }
 
diff --git a/zebra-chain/src/parameters/tests.rs b/zebra-chain/src/parameters/tests.rs
index 2b0f8b4a2..3c32f05a8 100644
--- a/zebra-chain/src/parameters/tests.rs
+++ b/zebra-chain/src/parameters/tests.rs
@@ -127,7 +127,7 @@ fn activation_consistent(network: Network) {
     for &network_upgrade in network_upgrades {
         let height = network_upgrade
             .activation_height(&network)
-            .expect("activations must have a height");
+            .expect("activations must have a height on default networks");
         assert!(NetworkUpgrade::is_activation_height(&network, height));
 
         if height > block::Height(0) {
diff --git a/zebra-chain/src/primitives/zcash_history/tests/vectors.rs b/zebra-chain/src/primitives/zcash_history/tests/vectors.rs
index d23cb078d..d7646a6cd 100644
--- a/zebra-chain/src/primitives/zcash_history/tests/vectors.rs
+++ b/zebra-chain/src/primitives/zcash_history/tests/vectors.rs
@@ -21,7 +21,10 @@ fn tree() -> Result<()> {
 fn tree_for_network_upgrade(network: &Network, network_upgrade: NetworkUpgrade) -> Result<()> {
     let (blocks, sapling_roots) = network.block_sapling_roots_map();
 
-    let height = network_upgrade.activation_height(network).unwrap().0;
+    let height = network_upgrade
+        .activation_height(network)
+        .expect("must have activation height on default network")
+        .0;
 
     // Load Block 0 (activation block of the given network upgrade)
     let block0 = Arc::new(
diff --git a/zebra-chain/src/sapling/tests/tree.rs b/zebra-chain/src/sapling/tests/tree.rs
index 37773e01e..aa3dd1e9e 100644
--- a/zebra-chain/src/sapling/tests/tree.rs
+++ b/zebra-chain/src/sapling/tests/tree.rs
@@ -62,7 +62,7 @@ fn incremental_roots_with_blocks_for_network(network: Network) -> Result<()> {
 
     let height = NetworkUpgrade::Sapling
         .activation_height(&network)
-        .unwrap()
+        .expect("must have activation height on default network")
         .0;
 
     // Build empty note commitment tree
diff --git a/zebra-chain/src/sprout/tests/tree.rs b/zebra-chain/src/sprout/tests/tree.rs
index f04ee9af3..1cf896854 100644
--- a/zebra-chain/src/sprout/tests/tree.rs
+++ b/zebra-chain/src/sprout/tests/tree.rs
@@ -92,7 +92,7 @@ fn incremental_roots_with_blocks_for_network(network: Network) -> Result<()> {
     // Load the Genesis height.
     let genesis_height = NetworkUpgrade::Genesis
         .activation_height(&network)
-        .unwrap()
+        .expect("must have activation height on default network")
         .0;
 
     // Load the Genesis block.
diff --git a/zebra-chain/src/transaction/tests/vectors.rs b/zebra-chain/src/transaction/tests/vectors.rs
index 7115d7f36..8fb1a8ddf 100644
--- a/zebra-chain/src/transaction/tests/vectors.rs
+++ b/zebra-chain/src/transaction/tests/vectors.rs
@@ -352,7 +352,7 @@ fn fake_v5_round_trip_for_network(network: Network) {
 
     let overwinter_activation_height = NetworkUpgrade::Overwinter
         .activation_height(&network)
-        .expect("a valid height")
+        .expect("must have activation height on default network")
         .0;
 
     // skip blocks that are before overwinter as they will not have a valid consensus branch id
@@ -500,7 +500,7 @@ fn fake_v5_librustzcash_round_trip_for_network(network: Network) {
 
     let overwinter_activation_height = NetworkUpgrade::Overwinter
         .activation_height(&network)
-        .expect("a valid height")
+        .expect("must have activation height on default network")
         .0;
 
     let nu5_activation_height = NetworkUpgrade::Nu5
diff --git a/zebra-consensus/src/block/check.rs b/zebra-consensus/src/block/check.rs
index 797df65c5..054a2d983 100644
--- a/zebra-consensus/src/block/check.rs
+++ b/zebra-consensus/src/block/check.rs
@@ -155,7 +155,7 @@ pub fn subsidy_is_valid(block: &Block, network: &Network) -> Result<(), BlockErr
 
     let canopy_activation_height = NetworkUpgrade::Canopy
         .activation_height(network)
-        .expect("Canopy activation height is known");
+        .expect("Canopy activation height is required for semantic block validation");
 
     if height < SLOW_START_INTERVAL {
         unreachable!(
diff --git a/zebra-consensus/src/block/subsidy/funding_streams.rs b/zebra-consensus/src/block/subsidy/funding_streams.rs
index c3389782b..c46068167 100644
--- a/zebra-consensus/src/block/subsidy/funding_streams.rs
+++ b/zebra-consensus/src/block/subsidy/funding_streams.rs
@@ -25,7 +25,9 @@ pub fn funding_stream_values(
     height: Height,
     network: &Network,
 ) -> Result<HashMap<FundingStreamReceiver, Amount<NonNegative>>, Error> {
-    let canopy_height = Canopy.activation_height(network).unwrap();
+    let canopy_height = Canopy
+        .activation_height(network)
+        .expect("requires Canopy activation height");
     let mut results = HashMap::new();
 
     if height >= canopy_height {
diff --git a/zebra-consensus/src/parameters/subsidy.rs b/zebra-consensus/src/parameters/subsidy.rs
index e7cf8f91b..1e0ac3a8d 100644
--- a/zebra-consensus/src/parameters/subsidy.rs
+++ b/zebra-consensus/src/parameters/subsidy.rs
@@ -230,7 +230,7 @@ impl ParameterSubsidy for Network {
         match self {
             Network::Mainnet => NetworkUpgrade::Canopy
                 .activation_height(self)
-                .expect("canopy activation height should be available"),
+                .expect("Canopy activation height should be available"),
             // TODO: Check what zcashd does here, consider adding a field to `testnet::Parameters` to make this configurable.
             Network::Testnet(_params) => FIRST_HALVING_TESTNET,
         }
diff --git a/zebra-consensus/src/transaction/check.rs b/zebra-consensus/src/transaction/check.rs
index 432f3d2f6..e96168d4c 100644
--- a/zebra-consensus/src/transaction/check.rs
+++ b/zebra-consensus/src/transaction/check.rs
@@ -356,7 +356,6 @@ pub fn coinbase_expiry_height(
 ) -> Result<(), TransactionError> {
     let expiry_height = coinbase.expiry_height();
 
-    // TODO: replace `if let` with `expect` after NU5 mainnet activation
     if let Some(nu5_activation_height) = NetworkUpgrade::Nu5.activation_height(network) {
         // # Consensus
         //
diff --git a/zebra-grpc/src/tests/snapshot.rs b/zebra-grpc/src/tests/snapshot.rs
index 6b81a3c70..dc19a3bec 100644
--- a/zebra-grpc/src/tests/snapshot.rs
+++ b/zebra-grpc/src/tests/snapshot.rs
@@ -88,7 +88,9 @@ async fn test_mocked_rpc_response_data_for_network(network: Network, random_port
                 .expect_request_that(|req| matches!(req, ScanRequest::Info))
                 .await
                 .respond(ScanResponse::Info {
-                    min_sapling_birthday_height: network.sapling_activation_height(),
+                    min_sapling_birthday_height: network
+                        .sapling_activation_height()
+                        .expect("must have Sapling activation height for default network"),
                 })
         });
     }
diff --git a/zebra-grpc/src/tests/vectors.rs b/zebra-grpc/src/tests/vectors.rs
index b34a8ec8b..e9a956bf1 100644
--- a/zebra-grpc/src/tests/vectors.rs
+++ b/zebra-grpc/src/tests/vectors.rs
@@ -57,7 +57,10 @@ async fn test_mocked_getinfo_for_network(
     // test the response
     assert_eq!(
         get_info_response.into_inner().min_sapling_birthday_height,
-        network.sapling_activation_height().0,
+        network
+            .sapling_activation_height()
+            .expect("must have Sapling activation height for default network")
+            .0,
         "get_info response min sapling height should match network sapling activation height"
     );
 }
@@ -396,7 +399,9 @@ async fn call_get_info(
             .expect_request_that(|req| matches!(req, ScanRequest::Info))
             .await
             .respond(ScanResponse::Info {
-                min_sapling_birthday_height: network.sapling_activation_height(),
+                min_sapling_birthday_height: network
+                    .sapling_activation_height()
+                    .expect("must have Sapling activation height for default network"),
             })
     });
 
diff --git a/zebra-scan/src/service.rs b/zebra-scan/src/service.rs
index 200160ab3..e8705f44a 100644
--- a/zebra-scan/src/service.rs
+++ b/zebra-scan/src/service.rs
@@ -95,7 +95,10 @@ impl Service<Request> for ScanService {
 
                 return async move {
                     Ok(Response::Info {
-                        min_sapling_birthday_height: db.network().sapling_activation_height(),
+                        min_sapling_birthday_height: db
+                            .network()
+                            .sapling_activation_height()
+                            .ok_or("missing Sapling activation height")?,
                     })
                 }
                 .boxed();
diff --git a/zebra-scan/src/service/scan_task/commands.rs b/zebra-scan/src/service/scan_task/commands.rs
index e718d742c..5f5ceb211 100644
--- a/zebra-scan/src/service/scan_task/commands.rs
+++ b/zebra-scan/src/service/scan_task/commands.rs
@@ -78,7 +78,9 @@ impl ScanTask {
         let mut new_keys = HashMap::new();
         let mut new_result_senders = HashMap::new();
         let mut new_result_receivers = Vec::new();
-        let sapling_activation_height = network.sapling_activation_height();
+        let sapling_activation_height = network.sapling_activation_height().ok_or(eyre!(
+            "must have Sapling activation height for default network"
+        ))?;
 
         loop {
             let cmd = match cmd_receiver.try_recv() {
diff --git a/zebra-scan/src/service/scan_task/scan.rs b/zebra-scan/src/service/scan_task/scan.rs
index 12bbb86a1..779fef5d5 100644
--- a/zebra-scan/src/service/scan_task/scan.rs
+++ b/zebra-scan/src/service/scan_task/scan.rs
@@ -79,7 +79,9 @@ pub async fn start(
     mut cmd_receiver: tokio::sync::mpsc::Receiver<ScanTaskCommand>,
 ) -> Result<(), Report> {
     let network = storage.network();
-    let sapling_activation_height = network.sapling_activation_height();
+    let sapling_activation_height = network
+        .sapling_activation_height()
+        .ok_or(eyre!("missing Sapling activation height"))?;
 
     info!(?network, "starting scan task");
 
diff --git a/zebra-scan/src/service/scan_task/scan/scan_range.rs b/zebra-scan/src/service/scan_task/scan/scan_range.rs
index b4b75cfe5..ce97e3249 100644
--- a/zebra-scan/src/service/scan_task/scan/scan_range.rs
+++ b/zebra-scan/src/service/scan_task/scan/scan_range.rs
@@ -6,7 +6,7 @@ use crate::{
     scan::{get_min_height, scan_height_and_store_results, wait_for_height, State, CHECK_INTERVAL},
     storage::Storage,
 };
-use color_eyre::eyre::Report;
+use color_eyre::eyre::{eyre, Report};
 use tokio::{
     sync::{mpsc::Sender, watch},
     task::JoinHandle,
@@ -88,7 +88,10 @@ pub async fn scan_range(
     storage: Storage,
     subscribed_keys_receiver: watch::Receiver<Arc<HashMap<String, Sender<ScanResult>>>>,
 ) -> Result<(), Report> {
-    let sapling_activation_height = storage.network().sapling_activation_height();
+    let sapling_activation_height = storage
+        .network()
+        .sapling_activation_height()
+        .ok_or(eyre!("missing Sapling activation height"))?;
     // Do not scan and notify if we are below sapling activation height.
     wait_for_height(
         sapling_activation_height,
diff --git a/zebra-scan/src/storage/db/sapling.rs b/zebra-scan/src/storage/db/sapling.rs
index b3c7b870b..4a24df106 100644
--- a/zebra-scan/src/storage/db/sapling.rs
+++ b/zebra-scan/src/storage/db/sapling.rs
@@ -213,7 +213,10 @@ impl Storage {
         sapling_key: &SaplingScanningKey,
         birthday_height: Option<Height>,
     ) {
-        let min_birthday_height = self.network().sapling_activation_height();
+        let min_birthday_height = self
+            .network()
+            .sapling_activation_height()
+            .unwrap_or(Height(1));
 
         // The birthday height must be at least the minimum height for that pool.
         let birthday_height = birthday_height
diff --git a/zebra-scan/src/tests/vectors.rs b/zebra-scan/src/tests/vectors.rs
index 9fff00c62..c5e47fcc3 100644
--- a/zebra-scan/src/tests/vectors.rs
+++ b/zebra-scan/src/tests/vectors.rs
@@ -170,7 +170,9 @@ fn scanning_fake_blocks_store_key_and_results() -> Result<()> {
             .expect("height is stored")
             .next()
             .expect("height is not maximum"),
-        network.sapling_activation_height()
+        network
+            .sapling_activation_height()
+            .expect("should have Sapling activation height on default networks")
     );
 
     let nf = Nullifier([7; 32]);
diff --git a/zebra-state/src/service.rs b/zebra-state/src/service.rs
index 203c1d34c..423ef50a7 100644
--- a/zebra-state/src/service.rs
+++ b/zebra-state/src/service.rs
@@ -423,9 +423,7 @@ impl StateService {
         let timer = CodeTimer::start();
 
         if let Some(tip) = state.best_tip() {
-            let nu5_activation_height = NetworkUpgrade::Nu5
-                .activation_height(network)
-                .expect("NU5 activation height is set");
+            let nu5_activation_height = NetworkUpgrade::Nu5.activation_height(network);
 
             if let Err(error) = check::legacy_chain(
                 nu5_activation_height,
diff --git a/zebra-state/src/service/check.rs b/zebra-state/src/service/check.rs
index 30144d8d3..a9b8cdf4f 100644
--- a/zebra-state/src/service/check.rs
+++ b/zebra-state/src/service/check.rs
@@ -306,7 +306,7 @@ fn difficulty_threshold_and_time_are_valid(
 /// `max_legacy_chain_blocks` should be [`MAX_LEGACY_CHAIN_BLOCKS`](crate::constants::MAX_LEGACY_CHAIN_BLOCKS).
 /// They are only changed from the defaults for testing.
 pub(crate) fn legacy_chain<I>(
-    nu5_activation_height: block::Height,
+    nu5_activation_height: Option<block::Height>,
     ancestors: I,
     network: &Network,
     max_legacy_chain_blocks: usize,
@@ -323,11 +323,7 @@ where
         //
         // If the cached tip is close to NU5 activation, but there aren't any V5 transactions in the
         // chain yet, we could reach MAX_BLOCKS_TO_CHECK in Canopy, and incorrectly return an error.
-        if block
-            .coinbase_height()
-            .expect("valid blocks have coinbase heights")
-            < nu5_activation_height
-        {
+        if block.coinbase_height() < nu5_activation_height {
             return Ok(());
         }
 
diff --git a/zebra-state/src/service/tests.rs b/zebra-state/src/service/tests.rs
index ca8d195af..7b447a405 100644
--- a/zebra-state/src/service/tests.rs
+++ b/zebra-state/src/service/tests.rs
@@ -306,7 +306,7 @@ proptest! {
     fn some_block_less_than_network_upgrade(
         (network, nu_activation_height, chain) in partial_nu5_chain_strategy(4, true, UNDER_LEGACY_CHAIN_LIMIT, NetworkUpgrade::Canopy)
     ) {
-        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), &network, TEST_LEGACY_CHAIN_LIMIT)
+        let response = crate::service::check::legacy_chain(Some(nu_activation_height), chain.into_iter().rev(), &network, TEST_LEGACY_CHAIN_LIMIT)
             .map_err(|error| error.to_string());
 
         prop_assert_eq!(response, Ok(()));
@@ -323,7 +323,7 @@ proptest! {
             .coinbase_height()
             .expect("chain contains valid blocks");
 
-        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), &network, TEST_LEGACY_CHAIN_LIMIT)
+        let response = crate::service::check::legacy_chain(Some(nu_activation_height), chain.into_iter().rev(), &network, TEST_LEGACY_CHAIN_LIMIT)
             .map_err(|error| error.to_string());
 
         prop_assert_eq!(
@@ -360,7 +360,7 @@ proptest! {
         );
 
         let response = crate::service::check::legacy_chain(
-            nu_activation_height,
+            Some(nu_activation_height),
             chain.clone().into_iter().rev(),
             &network,
             TEST_LEGACY_CHAIN_LIMIT,
@@ -380,7 +380,7 @@ proptest! {
     fn at_least_one_transaction_with_valid_network_upgrade(
         (network, nu_activation_height, chain) in partial_nu5_chain_strategy(5, true, UNDER_LEGACY_CHAIN_LIMIT, NetworkUpgrade::Canopy)
     ) {
-        let response = crate::service::check::legacy_chain(nu_activation_height, chain.into_iter().rev(), &network, TEST_LEGACY_CHAIN_LIMIT)
+        let response = crate::service::check::legacy_chain(Some(nu_activation_height), chain.into_iter().rev(), &network, TEST_LEGACY_CHAIN_LIMIT)
             .map_err(|error| error.to_string());
 
         prop_assert_eq!(response, Ok(()));