Simplify ancestor calculation functions

diff --git a/src/policy/rbf.cpp b/src/policy/rbf.cpp
index 19823464..fdf6f53c 100644
--- a/src/policy/rbf.cpp
+++ b/src/policy/rbf.cpp
@@ -39,8 +39,7 @@ RBFTransactionState IsRBFOptIn(const CTransaction& tx, const CTxMemPool& pool)
     // If all the inputs have nSequence >= maxint-1, it still might be
     // signaled for RBF if any unconfirmed parents have signaled.
     const auto& entry{*Assert(pool.GetEntry(tx.GetHash()))};
-    auto ancestors{pool.AssumeCalculateMemPoolAncestors(__func__, entry,
-                                                        /*fSearchForParents=*/false)};
+    auto ancestors{pool.CalculateMemPoolAncestors(entry, /*fSearchForParents=*/false)};
 
     for (CTxMemPool::txiter it : ancestors) {
         if (SignalsOptInRBF(it->GetTx())) {
diff --git a/src/rpc/mempool.cpp b/src/rpc/mempool.cpp
index d558a8cb..01870ef3 100644
--- a/src/rpc/mempool.cpp
+++ b/src/rpc/mempool.cpp
@@ -474,7 +474,7 @@ static RPCHelpMan getmempoolancestors()
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not in mempool");
     }
 
-    auto ancestors{mempool.AssumeCalculateMemPoolAncestors(self.m_name, *entry, /*fSearchForParents=*/false)};
+    auto ancestors{mempool.CalculateMemPoolAncestors(*entry, /*fSearchForParents=*/false)};
 
     if (!fVerbose) {
         UniValue o(UniValue::VARR);
diff --git a/src/test/txvalidation_tests.cpp b/src/test/txvalidation_tests.cpp
index 27f5d959..c0c9cc9c 100644
--- a/src/test/txvalidation_tests.cpp
+++ b/src/test/txvalidation_tests.cpp
@@ -296,7 +296,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         const auto expected_error_str{strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
             tx_v2_from_v3->GetHash().ToString(), tx_v2_from_v3->GetWitnessHash().ToString(),
             mempool_tx_v3->GetHash().ToString(), mempool_tx_v3->GetWitnessHash().ToString())};
-        auto result_v2_from_v3{SingleTRUCChecks(pool, tx_v2_from_v3, *ancestors_v2_from_v3, empty_conflicts_set, GetVirtualTransactionSize(*tx_v2_from_v3))};
+        auto result_v2_from_v3{SingleTRUCChecks(pool, tx_v2_from_v3, ancestors_v2_from_v3, empty_conflicts_set, GetVirtualTransactionSize(*tx_v2_from_v3))};
         BOOST_CHECK_EQUAL(result_v2_from_v3->first, expected_error_str);
         BOOST_CHECK_EQUAL(result_v2_from_v3->second, nullptr);
 
@@ -313,7 +313,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         const auto expected_error_str_2{strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
             tx_v2_from_v2_and_v3->GetHash().ToString(), tx_v2_from_v2_and_v3->GetWitnessHash().ToString(),
             mempool_tx_v3->GetHash().ToString(), mempool_tx_v3->GetWitnessHash().ToString())};
-        auto result_v2_from_both{SingleTRUCChecks(pool, tx_v2_from_v2_and_v3, *ancestors_v2_from_both, empty_conflicts_set, GetVirtualTransactionSize(*tx_v2_from_v2_and_v3))};
+        auto result_v2_from_both{SingleTRUCChecks(pool, tx_v2_from_v2_and_v3, ancestors_v2_from_both, empty_conflicts_set, GetVirtualTransactionSize(*tx_v2_from_v2_and_v3))};
         BOOST_CHECK_EQUAL(result_v2_from_both->first, expected_error_str_2);
         BOOST_CHECK_EQUAL(result_v2_from_both->second, nullptr);
 
@@ -331,7 +331,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         const auto expected_error_str{strprintf("version=3 tx %s (wtxid=%s) cannot spend from non-version=3 tx %s (wtxid=%s)",
             tx_v3_from_v2->GetHash().ToString(), tx_v3_from_v2->GetWitnessHash().ToString(),
             mempool_tx_v2->GetHash().ToString(), mempool_tx_v2->GetWitnessHash().ToString())};
-        auto result_v3_from_v2{SingleTRUCChecks(pool, tx_v3_from_v2, *ancestors_v3_from_v2,  empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_from_v2))};
+        auto result_v3_from_v2{SingleTRUCChecks(pool, tx_v3_from_v2, ancestors_v3_from_v2,  empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_from_v2))};
         BOOST_CHECK_EQUAL(result_v3_from_v2->first, expected_error_str);
         BOOST_CHECK_EQUAL(result_v3_from_v2->second, nullptr);
 
@@ -348,7 +348,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         const auto expected_error_str_2{strprintf("version=3 tx %s (wtxid=%s) cannot spend from non-version=3 tx %s (wtxid=%s)",
             tx_v3_from_v2_and_v3->GetHash().ToString(), tx_v3_from_v2_and_v3->GetWitnessHash().ToString(),
             mempool_tx_v2->GetHash().ToString(), mempool_tx_v2->GetWitnessHash().ToString())};
-        auto result_v3_from_both{SingleTRUCChecks(pool, tx_v3_from_v2_and_v3, *ancestors_v3_from_both, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_from_v2_and_v3))};
+        auto result_v3_from_both{SingleTRUCChecks(pool, tx_v3_from_v2_and_v3, ancestors_v3_from_both, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_from_v2_and_v3))};
         BOOST_CHECK_EQUAL(result_v3_from_both->first, expected_error_str_2);
         BOOST_CHECK_EQUAL(result_v3_from_both->second, nullptr);
 
@@ -365,7 +365,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         // tx_v3_from_v3
         auto tx_v3_from_v3 = make_tx({COutPoint{mempool_tx_v3->GetHash(), 0}}, /*version=*/3);
         auto ancestors_v3{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v3_from_v3))};
-        BOOST_CHECK(SingleTRUCChecks(pool, tx_v3_from_v3, *ancestors_v3, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_from_v3))
+        BOOST_CHECK(SingleTRUCChecks(pool, tx_v3_from_v3, ancestors_v3, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_from_v3))
                     == std::nullopt);
 
         Package package_v3_v3{mempool_tx_v3, tx_v3_from_v3};
@@ -376,7 +376,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         // tx_v2_from_v2
         auto tx_v2_from_v2 = make_tx({COutPoint{mempool_tx_v2->GetHash(), 0}}, /*version=*/2);
         auto ancestors_v2{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v2_from_v2))};
-        BOOST_CHECK(SingleTRUCChecks(pool, tx_v2_from_v2, *ancestors_v2, empty_conflicts_set, GetVirtualTransactionSize(*tx_v2_from_v2))
+        BOOST_CHECK(SingleTRUCChecks(pool, tx_v2_from_v2, ancestors_v2, empty_conflicts_set, GetVirtualTransactionSize(*tx_v2_from_v2))
                     == std::nullopt);
 
         Package package_v2_v2{mempool_tx_v2, tx_v2_from_v2};
@@ -399,10 +399,10 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         auto tx_v3_multi_parent = make_tx(mempool_outpoints, /*version=*/3);
         package_multi_parents.emplace_back(tx_v3_multi_parent);
         auto ancestors{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v3_multi_parent))};
-        BOOST_CHECK_EQUAL(ancestors->size(), 3);
+        BOOST_CHECK_EQUAL(ancestors.size(), 3);
         const auto expected_error_str{strprintf("tx %s (wtxid=%s) would have too many ancestors",
             tx_v3_multi_parent->GetHash().ToString(), tx_v3_multi_parent->GetWitnessHash().ToString())};
-        auto result{SingleTRUCChecks(pool, tx_v3_multi_parent, *ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_multi_parent))};
+        auto result{SingleTRUCChecks(pool, tx_v3_multi_parent, ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_multi_parent))};
         BOOST_CHECK_EQUAL(result->first, expected_error_str);
         BOOST_CHECK_EQUAL(result->second, nullptr);
 
@@ -427,7 +427,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         auto ancestors{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v3_multi_gen))};
         const auto expected_error_str{strprintf("tx %s (wtxid=%s) would have too many ancestors",
             tx_v3_multi_gen->GetHash().ToString(), tx_v3_multi_gen->GetWitnessHash().ToString())};
-        auto result{SingleTRUCChecks(pool, tx_v3_multi_gen, *ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_multi_gen))};
+        auto result{SingleTRUCChecks(pool, tx_v3_multi_gen, ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_multi_gen))};
         BOOST_CHECK_EQUAL(result->first, expected_error_str);
         BOOST_CHECK_EQUAL(result->second, nullptr);
 
@@ -445,7 +445,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         auto ancestors{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v3_child_big))};
         const auto expected_error_str{strprintf("version=3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
             tx_v3_child_big->GetHash().ToString(), tx_v3_child_big->GetWitnessHash().ToString(), vsize, TRUC_CHILD_MAX_VSIZE)};
-        auto result{SingleTRUCChecks(pool, tx_v3_child_big, *ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_child_big))};
+        auto result{SingleTRUCChecks(pool, tx_v3_child_big, ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_child_big))};
         BOOST_CHECK_EQUAL(result->first, expected_error_str);
         BOOST_CHECK_EQUAL(result->second, nullptr);
 
@@ -483,12 +483,12 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         BOOST_CHECK_EQUAL(total_sigops, tx_many_sigops->vin.size() * MAX_PUBKEYS_PER_MULTISIG);
         const int64_t bip141_vsize{GetVirtualTransactionSize(*tx_many_sigops)};
         // Weight limit is not reached...
-        BOOST_CHECK(SingleTRUCChecks(pool, tx_many_sigops, *ancestors, empty_conflicts_set, bip141_vsize) == std::nullopt);
+        BOOST_CHECK(SingleTRUCChecks(pool, tx_many_sigops, ancestors, empty_conflicts_set, bip141_vsize) == std::nullopt);
         // ...but sigop limit is.
         const auto expected_error_str{strprintf("version=3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
             tx_many_sigops->GetHash().ToString(), tx_many_sigops->GetWitnessHash().ToString(),
             total_sigops * DEFAULT_BYTES_PER_SIGOP / WITNESS_SCALE_FACTOR, TRUC_CHILD_MAX_VSIZE)};
-        auto result{SingleTRUCChecks(pool, tx_many_sigops, *ancestors, empty_conflicts_set,
+        auto result{SingleTRUCChecks(pool, tx_many_sigops, ancestors, empty_conflicts_set,
                                         GetVirtualTransactionSize(*tx_many_sigops, /*nSigOpCost=*/total_sigops, /*bytes_per_sigop=*/ DEFAULT_BYTES_PER_SIGOP))};
         BOOST_CHECK_EQUAL(result->first, expected_error_str);
         BOOST_CHECK_EQUAL(result->second, nullptr);
@@ -503,7 +503,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
     {
         BOOST_CHECK(GetTransactionWeight(*tx_mempool_v3_child) <= TRUC_CHILD_MAX_VSIZE * WITNESS_SCALE_FACTOR);
         auto ancestors{pool.CalculateMemPoolAncestors(entry.FromTx(tx_mempool_v3_child))};
-        BOOST_CHECK(SingleTRUCChecks(pool, tx_mempool_v3_child, *ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_mempool_v3_child)) == std::nullopt);
+        BOOST_CHECK(SingleTRUCChecks(pool, tx_mempool_v3_child, ancestors, empty_conflicts_set, GetVirtualTransactionSize(*tx_mempool_v3_child)) == std::nullopt);
         AddToMempool(pool, entry.FromTx(tx_mempool_v3_child));
 
         Package package_v3_1p1c{mempool_tx_v3, tx_mempool_v3_child};
@@ -517,13 +517,13 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         auto ancestors_1sibling{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v3_child2))};
         const auto expected_error_str{strprintf("tx %s (wtxid=%s) would exceed descendant count limit",
             mempool_tx_v3->GetHash().ToString(), mempool_tx_v3->GetWitnessHash().ToString())};
-        auto result_with_sibling_eviction{SingleTRUCChecks(pool, tx_v3_child2, *ancestors_1sibling, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_child2))};
+        auto result_with_sibling_eviction{SingleTRUCChecks(pool, tx_v3_child2, ancestors_1sibling, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_child2))};
         BOOST_CHECK_EQUAL(result_with_sibling_eviction->first, expected_error_str);
         // The other mempool child is returned to allow for sibling eviction.
         BOOST_CHECK_EQUAL(result_with_sibling_eviction->second, tx_mempool_v3_child);
 
         // If directly replacing the child, make sure there is no double-counting.
-        BOOST_CHECK(SingleTRUCChecks(pool, tx_v3_child2, *ancestors_1sibling, {tx_mempool_v3_child->GetHash()}, GetVirtualTransactionSize(*tx_v3_child2))
+        BOOST_CHECK(SingleTRUCChecks(pool, tx_v3_child2, ancestors_1sibling, {tx_mempool_v3_child->GetHash()}, GetVirtualTransactionSize(*tx_v3_child2))
                     == std::nullopt);
 
         Package package_v3_1p2c{mempool_tx_v3, tx_mempool_v3_child, tx_v3_child2};
@@ -537,7 +537,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         BOOST_CHECK_EQUAL(pool.GetDescendantCount(entry_mempool_parent), 3);
         auto ancestors_2siblings{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v3_child3))};
 
-        auto result_2children{SingleTRUCChecks(pool, tx_v3_child3, *ancestors_2siblings, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_child3))};
+        auto result_2children{SingleTRUCChecks(pool, tx_v3_child3, ancestors_2siblings, empty_conflicts_set, GetVirtualTransactionSize(*tx_v3_child3))};
         BOOST_CHECK_EQUAL(result_2children->first, expected_error_str);
         // The other mempool child is not returned because sibling eviction is not allowed.
         BOOST_CHECK_EQUAL(result_2children->second, nullptr);
@@ -557,7 +557,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         auto ancestors_3gen{pool.CalculateMemPoolAncestors(entry.FromTx(tx_to_submit))};
         const auto expected_error_str{strprintf("tx %s (wtxid=%s) would exceed descendant count limit",
             tx_mempool_grandparent->GetHash().ToString(), tx_mempool_grandparent->GetWitnessHash().ToString())};
-        auto result_3gen{SingleTRUCChecks(pool, tx_to_submit, *ancestors_3gen, empty_conflicts_set, GetVirtualTransactionSize(*tx_to_submit))};
+        auto result_3gen{SingleTRUCChecks(pool, tx_to_submit, ancestors_3gen, empty_conflicts_set, GetVirtualTransactionSize(*tx_to_submit))};
         BOOST_CHECK_EQUAL(result_3gen->first, expected_error_str);
         // The other mempool child is not returned because sibling eviction is not allowed.
         BOOST_CHECK_EQUAL(result_3gen->second, nullptr);
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index d16a5efc..f83b4544 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -99,7 +99,7 @@ void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<Txid>& vHashesToU
     }
 }
 
-util::Result<CTxMemPool::setEntries> CTxMemPool::CalculateAncestors(CTxMemPoolEntry::Parents& staged_ancestors) const
+CTxMemPool::setEntries CTxMemPool::CalculateAncestors(CTxMemPoolEntry::Parents& staged_ancestors) const
 {
     setEntries ancestors;
 
@@ -127,19 +127,6 @@ util::Result<CTxMemPool::setEntries> CTxMemPool::CalculateAncestors(CTxMemPoolEn
 util::Result<void> CTxMemPool::CheckPackageLimits(const Package& package,
                                                   const int64_t total_vsize) const
 {
-    CTxMemPoolEntry::Parents staged_ancestors;
-    for (const auto& tx : package) {
-        for (const auto& input : tx->vin) {
-            std::optional<txiter> piter = GetIter(input.prevout.hash);
-            if (piter) {
-                staged_ancestors.insert(**piter);
-            }
-        }
-    }
-
-    const auto ancestors{CalculateAncestors(staged_ancestors)};
-    // It's possible to overestimate the ancestor/descendant totals.
-    if (!ancestors.has_value()) return util::Error{Untranslated("possibly " + util::ErrorString(ancestors).original)};
     return {};
 }
 
@@ -151,7 +138,7 @@ bool CTxMemPool::HasDescendants(const Txid& txid) const
     return m_txgraph->GetDescendants(*entry, TxGraph::Level::MAIN).size() > 1;
 }
 
-util::Result<CTxMemPool::setEntries> CTxMemPool::CalculateMemPoolAncestors(
+CTxMemPool::setEntries CTxMemPool::CalculateMemPoolAncestors(
     const CTxMemPoolEntry &entry,
     bool fSearchForParents /* = true */) const
 {
@@ -178,19 +165,6 @@ util::Result<CTxMemPool::setEntries> CTxMemPool::CalculateMemPoolAncestors(
     return CalculateAncestors(staged_ancestors);
 }
 
-CTxMemPool::setEntries CTxMemPool::AssumeCalculateMemPoolAncestors(
-    std::string_view calling_fn_name,
-    const CTxMemPoolEntry &entry,
-    bool fSearchForParents /* = true */) const
-{
-    auto result{CalculateMemPoolAncestors(entry, fSearchForParents)};
-    if (!Assume(result)) {
-        LogPrintLevel(BCLog::MEMPOOL, BCLog::Level::Error, "%s: CalculateMemPoolAncestors failed unexpectedly, continuing with empty ancestor set (%s)\n",
-                      calling_fn_name, util::ErrorString(result).original);
-    }
-    return std::move(result).value_or(CTxMemPool::setEntries{});
-}
-
 void CTxMemPool::UpdateAncestorsOf(bool add, txiter it)
 {
     const CTxMemPoolEntry::Parents& parents = it->GetMemPoolParentsConst();
@@ -264,16 +238,6 @@ void CTxMemPool::Apply(ChangeSet* changeset)
 
     for (size_t i=0; i<changeset->m_entry_vec.size(); ++i) {
         auto tx_entry = changeset->m_entry_vec[i];
-        std::optional<CTxMemPool::setEntries> ancestors;
-        if (i == 0) {
-            // Note: ChangeSet::CalculateMemPoolAncestors() will return a
-            // cached value if mempool ancestors for this transaction were
-            // previously calculated.
-            // We can only use a cached ancestor calculation for the first
-            // transaction in a package, because in-package parents won't be
-            // present in the cached ancestor sets of in-package children.
-            ancestors = *Assume(changeset->CalculateMemPoolAncestors(tx_entry));
-        }
         // First splice this entry into mapTx.
         auto node_handle = changeset->m_to_add.extract(tx_entry);
         auto result = mapTx.insert(std::move(node_handle));
@@ -281,22 +245,11 @@ void CTxMemPool::Apply(ChangeSet* changeset)
         Assume(result.inserted);
         txiter it = result.position;
 
-        // Now update the entry for ancestors/descendants.
-        if (ancestors.has_value()) {
-            addNewTransaction(it, *ancestors);
-        } else {
-            addNewTransaction(it);
-        }
+        addNewTransaction(it);
     }
 }
 
-void CTxMemPool::addNewTransaction(CTxMemPool::txiter it)
-{
-    auto ancestors{AssumeCalculateMemPoolAncestors(__func__, *it)};
-    return addNewTransaction(it, ancestors);
-}
-
-void CTxMemPool::addNewTransaction(CTxMemPool::txiter newit, CTxMemPool::setEntries& setAncestors)
+void CTxMemPool::addNewTransaction(CTxMemPool::txiter newit)
 {
     const CTxMemPoolEntry& entry = *newit;
 
diff --git a/src/txmempool.h b/src/txmempool.h
index cdf9bcc9..d2b7f232 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -310,9 +310,9 @@ private:
      *
      * @param[in]   staged_ancestors    Should contain entries in the mempool.
      *
-     * @return all in-mempool ancestors, or an error if any ancestor or descendant limits were hit
+     * @return all in-mempool ancestors
      */
-    util::Result<setEntries> CalculateAncestors(CTxMemPoolEntry::Parents &staged_ancestors)
+    setEntries CalculateAncestors(CTxMemPoolEntry::Parents &staged_ancestors)
             const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     static TxMempoolInfo GetInfo(CTxMemPool::indexed_transaction_set::const_iterator it)
@@ -429,7 +429,7 @@ public:
     }
 
     /**
-     * Try to calculate all in-mempool ancestors of entry.
+     * Calculate all in-mempool ancestors of entry.
      * (these are all calculated including the tx itself)
      *
      * @param[in]   entry               CTxMemPoolEntry of which all in-mempool ancestors are calculated
@@ -439,28 +439,9 @@ public:
      *
      * @return all in-mempool ancestors
      */
-    util::Result<setEntries> CalculateMemPoolAncestors(const CTxMemPoolEntry& entry,
+    setEntries CalculateMemPoolAncestors(const CTxMemPoolEntry& entry,
                                    bool fSearchForParents = true) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
-    /**
-     * Same as CalculateMemPoolAncestors, but always returns a (non-optional) setEntries.
-     * Should only be used when it is assumed CalculateMemPoolAncestors would not fail. If
-     * CalculateMemPoolAncestors does unexpectedly fail, an empty setEntries is returned and the
-     * error is logged to BCLog::MEMPOOL with level BCLog::Level::Error. In debug builds, failure
-     * of CalculateMemPoolAncestors will lead to shutdown due to assertion failure.
-     *
-     * @param[in]   calling_fn_name     Name of calling function so we can properly log the call site
-     *
-     * @return a setEntries corresponding to the result of CalculateMemPoolAncestors or an empty
-     *         setEntries if it failed
-     *
-     * @see CTXMemPool::CalculateMemPoolAncestors()
-     */
-    setEntries AssumeCalculateMemPoolAncestors(
-        std::string_view calling_fn_name,
-        const CTxMemPoolEntry &entry,
-        bool fSearchForParents = true) const EXCLUSIVE_LOCKS_REQUIRED(cs);
-
     bool HasDescendants(const Txid& txid) const;
 
     /** Collect the entire cluster of connected transactions for each transaction in txids.
@@ -722,7 +703,7 @@ public:
         /** Check if any cluster limits are exceeded. Returns true if pass, false if fail. */
         bool CheckMemPoolPolicyLimits();
 
-        util::Result<CTxMemPool::setEntries> CalculateMemPoolAncestors(TxHandle tx)
+        CTxMemPool::setEntries CalculateMemPoolAncestors(TxHandle tx)
         {
             // Look up transaction in our cache first
             auto it = m_ancestors.find(tx);
@@ -731,8 +712,8 @@ public:
             // If not found, try to have the mempool calculate it, and cache
             // for later.
             LOCK(m_pool->cs);
-            auto ret{m_pool->CalculateMemPoolAncestors(*tx)};
-            if (ret) m_ancestors.try_emplace(tx, *ret);
+            auto ret = m_pool->CalculateMemPoolAncestors(*tx);
+            m_ancestors.try_emplace(tx, ret);
             return ret;
         }
 
@@ -796,7 +777,6 @@ private:
     // tracking (due to lack of CValidationInterface::TransactionAddedToMempool
     // callbacks).
     void addNewTransaction(CTxMemPool::txiter it) EXCLUSIVE_LOCKS_REQUIRED(cs);
-    void addNewTransaction(CTxMemPool::txiter it, CTxMemPool::setEntries& setAncestors) EXCLUSIVE_LOCKS_REQUIRED(cs);
 public:
     void StartBlockBuilding() const EXCLUSIVE_LOCKS_REQUIRED(cs) { assert(!m_builder); m_builder = m_txgraph->GetBlockBuilder(); }
     FeePerWeight GetBlockBuilderChunk(std::vector<CTxMemPoolEntry::CTxMemPoolEntryRef>& entries) const EXCLUSIVE_LOCKS_REQUIRED(cs)
diff --git a/src/validation.cpp b/src/validation.cpp
index 49f8af3e..6a02acd5 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -961,12 +961,7 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
 
     ws.m_iters_conflicting = m_pool.GetIterSet(ws.m_conflicts);
 
-    // Calculate in-mempool ancestors, up to a limit.
-    if (auto ancestors{m_subpackage.m_changeset->CalculateMemPoolAncestors(ws.m_tx_handle)}) {
-        ws.m_ancestors = std::move(*ancestors);
-    } else {
-        return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "too-long-mempool-chain", util::ErrorString(ancestors).original);
-    }
+    ws.m_ancestors = m_subpackage.m_changeset->CalculateMemPoolAncestors(ws.m_tx_handle);
 
     // Even though just checking direct mempool parents for inheritance would be sufficient, we
     // check using the full ancestor set here because it's more convenient to use what we have