bitcoin · Sjors · Mar 18, 2026 · Mar 19, 2026 · Mar 18, 2026 · Mar 19, 2026
diff --git a/src/bench/block_assemble.cpp b/src/bench/block_assemble.cpp
@@ -30,7 +30,6 @@ static void AssembleBlock(benchmark::Bench& bench)
     witness.stack.push_back(WITNESS_STACK_ELEM_OP_TRUE);
     BlockAssembler::Options options;
     options.coinbase_output_script = P2WSH_OP_TRUE;
-    options.include_dummy_extranonce = true;
 
     // Collect some loose transactions that spend the coinbases of our mined blocks
     constexpr size_t NUM_BLOCKS{200};

diff --git a/src/kernel/chainparams.cpp b/src/kernel/chainparams.cpp
@@ -646,9 +646,9 @@ class CRegTestParams : public CChainParams
         m_assumeutxo_data = {
             {   // For use by unit tests
                 .height = 110,
-                .hash_serialized = AssumeutxoHash{uint256{"b952555c8ab81fec46f3d4253b7af256d766ceb39fb7752b9d18cdf4a0141327"}},
+                .hash_serialized = AssumeutxoHash{uint256{"86e9a1205b418b16dde3a18a78c730e30137e28466bda5dbf6b33ab8fc05447c"}},
                 .m_chain_tx_count = 111,
-                .blockhash = uint256{"6affe030b7965ab538f820a56ef56c8149b7dc1d1c144af57113be080db7c397"},
+                .blockhash = uint256{"135eec25a6fb277884e5824e7aa7d052c4868161c99a5122170b5266f86c273d"},
             },
             {
                 // For use by fuzz target src/test/fuzz/utxo_snapshot.cpp
@@ -660,9 +660,9 @@ class CRegTestParams : public CChainParams
             {
                 // For use by test/functional/feature_assumeutxo.py and test/functional/tool_bitcoin_chainstate.py
                 .height = 299,
-                .hash_serialized = AssumeutxoHash{uint256{"d2b051ff5e8eef46520350776f4100dd710a63447a8e01d917e92e79751a63e2"}},
+                .hash_serialized = AssumeutxoHash{uint256{"106b2c56233e378a824cf0d5ff2be42ed32c72f1605c9be288d00942908a40ac"}},
                 .m_chain_tx_count = 334,
-                .blockhash = uint256{"7cc695046fec709f8c9394b6f928f81e81fd3ac20977bb68760fa1faa7916ea2"},
+                .blockhash = uint256{"0c552ced4721c249a389eb9b08cb8da261cd46f0e7b5f9d064d48f3113406853"},
             },
         };
 

diff --git a/src/node/miner.cpp b/src/node/miner.cpp
@@ -184,14 +184,18 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock()
     // increasing its length would reduce the space they can use and may break
     // existing clients.
     coinbaseTx.vin[0].scriptSig = CScript() << nHeight;
-    if (m_options.include_dummy_extranonce) {
+    // Set script_sig_prefix here, so IPC mining clients are not affected by
+    // the optional scriptSig padding below. They provide their own extraNonce,
+    // and in a typical setup a pool name or realistic extraNonce already makes
+    // the scriptSig long enough.
+    coinbase_tx.script_sig_prefix = coinbaseTx.vin[0].scriptSig;
+    if (nHeight <= 16) {
         // For blocks at heights <= 16, the BIP34-encoded height alone is only
         // one byte. Consensus requires coinbase scriptSigs to be at least two
-        // bytes long (bad-cb-length), so tests and regtest include a dummy
-        // extraNonce (OP_0)
+        // bytes long (bad-cb-length), so an OP_0 is always appended at those
+        // heights.
         coinbaseTx.vin[0].scriptSig << OP_0;
     }
-    coinbase_tx.script_sig_prefix = coinbaseTx.vin[0].scriptSig;
     Assert(nHeight > 0);
     coinbaseTx.nLockTime = static_cast<uint32_t>(nHeight - 1);
     coinbase_tx.lock_time = coinbaseTx.nLockTime;
@@ -221,7 +225,6 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock()
     pblock->nNonce         = 0;
 
     if (m_options.test_block_validity) {
-        // if nHeight <= 16, and include_dummy_extranonce=false this will fail due to bad-cb-length.
         if (BlockValidationState state{TestBlockValidity(m_chainstate, *pblock, /*check_pow=*/false, /*check_merkle_root=*/false)}; !state.IsValid()) {
             throw std::runtime_error(strprintf("TestBlockValidity failed: %s", state.ToString()));
         }

diff --git a/src/node/types.h b/src/node/types.h
@@ -72,10 +72,6 @@ struct BlockCreateOptions {
      * coinbase_max_additional_weight and coinbase_output_max_additional_sigops.
      */
     CScript coinbase_output_script{CScript() << OP_TRUE};
-    /**
-     * Whether to include an OP_0 as a dummy extraNonce in the template's coinbase
-     */
-    bool include_dummy_extranonce{false};
 };
 
 struct BlockWaitOptions {

diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
@@ -165,7 +165,7 @@ static UniValue generateBlocks(ChainstateManager& chainman, Mining& miner, const
 {
     UniValue blockHashes(UniValue::VARR);
     while (nGenerate > 0 && !chainman.m_interrupt) {
-        std::unique_ptr<BlockTemplate> block_template(miner.createNewBlock({ .coinbase_output_script = coinbase_output_script, .include_dummy_extranonce = true }, /*cooldown=*/false));
+        std::unique_ptr<BlockTemplate> block_template(miner.createNewBlock({ .coinbase_output_script = coinbase_output_script }, /*cooldown=*/false));
         CHECK_NONFATAL(block_template);
 
         std::shared_ptr<const CBlock> block_out;
@@ -376,7 +376,7 @@ static RPCHelpMan generateblock()
     {
         LOCK(chainman.GetMutex());
         {
-            std::unique_ptr<BlockTemplate> block_template{miner.createNewBlock({.use_mempool = false, .coinbase_output_script = coinbase_output_script, .include_dummy_extranonce = true}, /*cooldown=*/false)};
+            std::unique_ptr<BlockTemplate> block_template{miner.createNewBlock({.use_mempool = false, .coinbase_output_script = coinbase_output_script}, /*cooldown=*/false)};
             CHECK_NONFATAL(block_template);
 
             block = block_template->getBlock();
@@ -874,7 +874,7 @@ static RPCHelpMan getblocktemplate()
         // a delay to each getblocktemplate call. This differs from typical
         // long-lived IPC usage, where the overhead is paid only when creating
         // the initial template.
-        block_template = miner.createNewBlock({.include_dummy_extranonce = true}, /*cooldown=*/false);
+        block_template = miner.createNewBlock({}, /*cooldown=*/false);
         CHECK_NONFATAL(block_template);
 
 

diff --git a/src/test/blockfilter_index_tests.cpp b/src/test/blockfilter_index_tests.cpp
@@ -70,7 +70,6 @@ CBlock BuildChainTestingSetup::CreateBlock(const CBlockIndex* prev,
 {
     BlockAssembler::Options options;
     options.coinbase_output_script = scriptPubKey;
-    options.include_dummy_extranonce = true;
     std::unique_ptr<CBlockTemplate> pblocktemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), m_node.mempool.get(), options}.CreateNewBlock();
     CBlock& block = pblocktemplate->block;
     block.hashPrevBlock = prev->GetBlockHash();

diff --git a/src/test/fuzz/package_eval.cpp b/src/test/fuzz/package_eval.cpp
@@ -46,7 +46,6 @@ void initialize_tx_pool()
 
     BlockAssembler::Options options;
     options.coinbase_output_script = P2WSH_EMPTY;
-    options.include_dummy_extranonce = true;
 
     for (int i = 0; i < 2 * COINBASE_MATURITY; ++i) {
         COutPoint prevout{MineBlock(g_setup->m_node, options)};

diff --git a/src/test/fuzz/process_message.cpp b/src/test/fuzz/process_message.cpp
@@ -43,7 +43,6 @@ void ResetChainman(TestingSetup& setup)
     setup.LoadVerifyActivateChainstate();
     for (int i = 0; i < 2 * COINBASE_MATURITY; i++) {
         node::BlockAssembler::Options options;
-        options.include_dummy_extranonce = true;
         MineBlock(setup.m_node, options);
     }
 }

diff --git a/src/test/fuzz/process_messages.cpp b/src/test/fuzz/process_messages.cpp
@@ -37,7 +37,6 @@ void ResetChainman(TestingSetup& setup)
     setup.m_make_chainman();
     setup.LoadVerifyActivateChainstate();
     node::BlockAssembler::Options options;
-    options.include_dummy_extranonce = true;
     for (int i = 0; i < 2 * COINBASE_MATURITY; i++) {
         MineBlock(setup.m_node, options);
     }

diff --git a/src/test/fuzz/tx_pool.cpp b/src/test/fuzz/tx_pool.cpp
@@ -48,7 +48,6 @@ void initialize_tx_pool()
 
     BlockAssembler::Options options;
     options.coinbase_output_script = P2WSH_OP_TRUE;
-    options.include_dummy_extranonce = true;
 
     for (int i = 0; i < 2 * COINBASE_MATURITY; ++i) {
         COutPoint prevout{MineBlock(g_setup->m_node, options)};
@@ -98,7 +97,6 @@ void Finish(FuzzedDataProvider& fuzzed_data_provider, MockedTxPool& tx_pool, Cha
         BlockAssembler::Options options;
         options.nBlockMaxWeight = fuzzed_data_provider.ConsumeIntegralInRange(0U, MAX_BLOCK_WEIGHT);
         options.blockMinFeeRate = CFeeRate{ConsumeMoney(fuzzed_data_provider, /*max=*/COIN)};
-        options.include_dummy_extranonce = true;
         auto assembler = BlockAssembler{chainstate, &tx_pool, options};
         auto block_template = assembler.CreateNewBlock();
         Assert(block_template->block.vtx.size() >= 1);

diff --git a/src/test/fuzz/utxo_total_supply.cpp b/src/test/fuzz/utxo_total_supply.cpp
@@ -46,7 +46,6 @@ FUZZ_TARGET(utxo_total_supply)
     };
     BlockAssembler::Options options;
     options.coinbase_output_script = CScript() << OP_FALSE;
-    options.include_dummy_extranonce = true;
     const auto PrepareNextBlock = [&]() {
         // Use OP_FALSE to avoid BIP30 check from hitting early
         auto block = PrepareBlock(node, options);
@@ -107,8 +106,13 @@ FUZZ_TARGET(utxo_total_supply)
     // Assuming that the fuzzer will mine relatively short chains (less than 200 blocks), we want the duplicate coinbase to be not too high.
     // Up to 300 seems reasonable.
     int64_t duplicate_coinbase_height = fuzzed_data_provider.ConsumeIntegralInRange(0, 300);
-    // Always pad with OP_0 at the end to avoid bad-cb-length error
-    const CScript duplicate_coinbase_script = CScript() << duplicate_coinbase_height << OP_0;
+    // Build the scriptSig exactly as CreateNewBlock does for the given height:
+    // BIP34-encoded height, plus OP_0 padding at heights <= 16 to satisfy
+    // the minimum 2-byte coinbase scriptSig length (bad-cb-length).
+    CScript duplicate_coinbase_script = CScript() << duplicate_coinbase_height;
+    if (duplicate_coinbase_height <= 16) {
+        duplicate_coinbase_script << OP_0;
+    }
     // Mine the first block with this duplicate
     current_block = PrepareNextBlock();
     StoreLastTxo();

diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
@@ -117,7 +117,6 @@ void MinerTestingSetup::TestPackageSelection(const CScript& scriptPubKey, const
     auto mining{MakeMining()};
     BlockAssembler::Options options;
     options.coinbase_output_script = scriptPubKey;
-    options.include_dummy_extranonce = true;
 
     LOCK(tx_mempool.cs);
     BOOST_CHECK(tx_mempool.size() == 0);
@@ -336,7 +335,6 @@ void MinerTestingSetup::TestBasicMining(const CScript& scriptPubKey, const std::
 
     BlockAssembler::Options options;
     options.coinbase_output_script = scriptPubKey;
-    options.include_dummy_extranonce = true;
 
     {
         CTxMemPool& tx_mempool{MakeMempool()};
@@ -663,7 +661,6 @@ void MinerTestingSetup::TestPrioritisedMining(const CScript& scriptPubKey, const
 
     BlockAssembler::Options options;
     options.coinbase_output_script = scriptPubKey;
-    options.include_dummy_extranonce = true;
 
     CTxMemPool& tx_mempool{MakeMempool()};
     LOCK(tx_mempool.cs);
@@ -753,7 +750,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
     CScript scriptPubKey = CScript() << "04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f"_hex << OP_CHECKSIG;
     BlockAssembler::Options options;
     options.coinbase_output_script = scriptPubKey;
-    options.include_dummy_extranonce = true;
 
     // Create and check a simple template
     std::unique_ptr<BlockTemplate> block_template = mining->createNewBlock(options, /*cooldown=*/false);

diff --git a/src/test/peerman_tests.cpp b/src/test/peerman_tests.cpp
@@ -20,7 +20,6 @@ static void mineBlock(const node::NodeContext& node, std::chrono::seconds block_
 {
     auto curr_time = GetTime<std::chrono::seconds>();
     node::BlockAssembler::Options options;
-    options.include_dummy_extranonce = true;
     SetMockTime(block_time); // update time so the block is created with it
     CBlock block = node::BlockAssembler{node.chainman->ActiveChainstate(), nullptr, options}.CreateNewBlock()->block;
     while (!CheckProofOfWork(block.GetHash(), block.nBits, node.chainman->GetConsensus())) ++block.nNonce;

diff --git a/src/test/testnet4_miner_tests.cpp b/src/test/testnet4_miner_tests.cpp
@@ -35,7 +35,6 @@ BOOST_AUTO_TEST_CASE(MiningInterface)
     BOOST_REQUIRE(mining);
 
     BlockAssembler::Options options;
-    options.include_dummy_extranonce = true;
     std::unique_ptr<BlockTemplate> block_template;
 
     // Set node time a few minutes past the testnet4 genesis block

diff --git a/src/test/util/mining.cpp b/src/test/util/mining.cpp
@@ -29,7 +29,6 @@ COutPoint generatetoaddress(const NodeContext& node, const std::string& address)
     assert(IsValidDestination(dest));
     BlockAssembler::Options assembler_options;
     assembler_options.coinbase_output_script = GetScriptForDestination(dest);
-    assembler_options.include_dummy_extranonce = true;
 
     return MineBlock(node, assembler_options);
 }
@@ -140,7 +139,6 @@ std::shared_ptr<CBlock> PrepareBlock(const NodeContext& node, const CScript& coi
 {
     BlockAssembler::Options assembler_options;
     assembler_options.coinbase_output_script = coinbase_scriptPubKey;
-    assembler_options.include_dummy_extranonce = true;
     ApplyArgsManOptions(*node.args, assembler_options);
     return PrepareBlock(node, assembler_options);
 }
diff --git a/src/test/util/setup_common.cpp b/src/test/util/setup_common.cpp
@@ -391,7 +391,7 @@ TestChain100Setup::TestChain100Setup(
         LOCK(::cs_main);
         assert(
             m_node.chainman->ActiveChain().Tip()->GetBlockHash().ToString() ==
-            "0c8c5f79505775a0f6aed6aca2350718ceb9c6f2c878667864d5c7a6d8ffa2a6");
+            "0ee6e270d6594249e548110619f7bd690695beb219b915da4a2e84e2b61ed60f");
     }
 }
 
@@ -413,7 +413,6 @@ CBlock TestChain100Setup::CreateBlock(
 {
     BlockAssembler::Options options;
     options.coinbase_output_script = scriptPubKey;
-    options.include_dummy_extranonce = true;
     CBlock block = BlockAssembler{chainstate, nullptr, options}.CreateNewBlock()->block;
 
     Assert(block.vtx.size() == 1);

diff --git a/src/test/validation_block_tests.cpp b/src/test/validation_block_tests.cpp
@@ -69,7 +69,6 @@ std::shared_ptr<CBlock> MinerTestingSetup::Block(const uint256& prev_hash)
 
     BlockAssembler::Options options;
     options.coinbase_output_script = CScript{} << i++ << OP_TRUE;
-    options.include_dummy_extranonce = true;
     auto ptemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), m_node.mempool.get(), options}.CreateNewBlock();
     auto pblock = std::make_shared<CBlock>(ptemplate->block);
     pblock->hashPrevBlock = prev_hash;
@@ -338,7 +337,6 @@ BOOST_AUTO_TEST_CASE(witness_commitment_index)
     pubKey << 1 << OP_TRUE;
     BlockAssembler::Options options;
     options.coinbase_output_script = pubKey;
-    options.include_dummy_extranonce = true;
     auto ptemplate = BlockAssembler{m_node.chainman->ActiveChainstate(), m_node.mempool.get(), options}.CreateNewBlock();
     CBlock pblock = ptemplate->block;
 

diff --git a/src/test/validation_tests.cpp b/src/test/validation_tests.cpp
@@ -142,11 +142,11 @@ BOOST_AUTO_TEST_CASE(test_assumeutxo)
     }
 
     const auto out110 = *params->AssumeutxoForHeight(110);
-    BOOST_CHECK_EQUAL(out110.hash_serialized.ToString(), "b952555c8ab81fec46f3d4253b7af256d766ceb39fb7752b9d18cdf4a0141327");
+    BOOST_CHECK_EQUAL(out110.hash_serialized.ToString(), "86e9a1205b418b16dde3a18a78c730e30137e28466bda5dbf6b33ab8fc05447c");
     BOOST_CHECK_EQUAL(out110.m_chain_tx_count, 111U);
 
-    const auto out110_2 = *params->AssumeutxoForBlockhash(uint256{"6affe030b7965ab538f820a56ef56c8149b7dc1d1c144af57113be080db7c397"});
-    BOOST_CHECK_EQUAL(out110_2.hash_serialized.ToString(), "b952555c8ab81fec46f3d4253b7af256d766ceb39fb7752b9d18cdf4a0141327");
+    const auto out110_2 = *params->AssumeutxoForBlockhash(uint256{"135eec25a6fb277884e5824e7aa7d052c4868161c99a5122170b5266f86c273d"});
+    BOOST_CHECK_EQUAL(out110_2.hash_serialized.ToString(), "86e9a1205b418b16dde3a18a78c730e30137e28466bda5dbf6b33ab8fc05447c");
     BOOST_CHECK_EQUAL(out110_2.m_chain_tx_count, 111U);
 }
 

diff --git a/test/functional/feature_assumeutxo.py b/test/functional/feature_assumeutxo.py
@@ -141,12 +141,12 @@ def expected_error(msg):
         self.log.info("  - snapshot file with alternated but parsable UTXO data results in different hash")
         cases = [
             # (content, offset, wrong_hash, custom_message)
-            [b"\xff" * 32, 0, "77874d48d932a5cb7a7f770696f5224ff05746fdcf732a58270b45da0f665934", None],  # wrong outpoint hash
-            [(2).to_bytes(1, "little"), 32, None, "Bad snapshot format or truncated snapshot after deserializing 1 coins."],  # wrong txid coins count
+            [b"\xff" * 32, 0, "43bb0fcc50f3789d50ce41891810bbc571d549a32e2bbaabfc036f73ae2a23f9", None],  # wrong outpoint hash
+            [(2).to_bytes(1, "little"), 32, None, "Bad snapshot data after deserializing 2 coins."],  # wrong txid coins count
             [b"\xfd\xff\xff", 32, None, "Mismatch in coins count in snapshot metadata and actual snapshot data"],  # txid coins count exceeds coins left
-            [b"\x01", 33, "9f562925721e4f97e6fde5b590dbfede51e2204a68639525062ad064545dd0ea", None],  # wrong outpoint index
-            [b"\x82", 34, "161393f07f8ad71760b3910a914f677f2cb166e5bcf5354e50d46b78c0422d15", None],  # wrong coin code VARINT
-            [b"\x80", 34, "e6fae191ef851554467b68acff01ca09ad0a2e48c9b3dfea46cf7d35a7fd0ad0", None],  # another wrong coin code
+            [b"\x01", 33, "0b0e96fd9a556157a68d9e6fe6e2c7562169c730347565ce0725032f824bea34", None],  # wrong outpoint index
+            [b"\x83", 34, "52084c732f760fbcfb804d854815a9145111e93d7c7f3f7bfcb0ade1ea4f6b99", None],  # wrong coin code VARINT
+            [b"\x80", 34, "c1a1308fcf04cbb14fc777467eb5e98e77a921b66eac4ad47877d0b6ed7b15b1", None],  # another wrong coin code
             [b"\x84\x58", 34, None, "Bad snapshot data after deserializing 0 coins"],  # wrong coin case with height 364 and coinbase 0
             [
                 # compressed txout value + scriptpubkey
@@ -165,12 +165,12 @@ def expected_error(msg):
                 f.write(content)
                 f.write(valid_snapshot_contents[(5 + 2 + 4 + 32 + 8 + offset + len(content)):])
 
-            msg = custom_message if custom_message is not None else f"Bad snapshot content hash: expected d2b051ff5e8eef46520350776f4100dd710a63447a8e01d917e92e79751a63e2, got {wrong_hash}."
+            msg = custom_message if custom_message is not None else f"Bad snapshot content hash: expected 106b2c56233e378a824cf0d5ff2be42ed32c72f1605c9be288d00942908a40ac, got {wrong_hash}."
             expected_error(msg)
 
     def test_headers_not_synced(self, valid_snapshot_path):
         for node in self.nodes[1:]:
-            msg = "Unable to load UTXO snapshot: The base block header (7cc695046fec709f8c9394b6f928f81e81fd3ac20977bb68760fa1faa7916ea2) must appear in the headers chain. Make sure all headers are syncing, and call loadtxoutset again."
+            msg = "Unable to load UTXO snapshot: The base block header (0c552ced4721c249a389eb9b08cb8da261cd46f0e7b5f9d064d48f3113406853) must appear in the headers chain. Make sure all headers are syncing, and call loadtxoutset again."
             assert_raises_rpc_error(-32603, msg, node.loadtxoutset, valid_snapshot_path)
 
     def test_invalid_chainstate_scenarios(self):
@@ -229,7 +229,7 @@ def test_snapshot_block_invalidated(self, dump_output_path):
             block_hash = node.getblockhash(height)
             node.invalidateblock(block_hash)
             assert_equal(node.getblockcount(), height - 1)
-            msg = "Unable to load UTXO snapshot: The base block header (7cc695046fec709f8c9394b6f928f81e81fd3ac20977bb68760fa1faa7916ea2) is part of an invalid chain."
+            msg = "Unable to load UTXO snapshot: The base block header (0c552ced4721c249a389eb9b08cb8da261cd46f0e7b5f9d064d48f3113406853) is part of an invalid chain."
             assert_raises_rpc_error(-32603, msg, node.loadtxoutset, dump_output_path)
             node.reconsiderblock(block_hash)
 
@@ -470,7 +470,7 @@ def run_test(self):
         def check_dump_output(output):
             assert_equal(
                 output['txoutset_hash'],
-                "d2b051ff5e8eef46520350776f4100dd710a63447a8e01d917e92e79751a63e2")
+                "106b2c56233e378a824cf0d5ff2be42ed32c72f1605c9be288d00942908a40ac")
             assert_equal(output["nchaintx"], blocks[SNAPSHOT_BASE_HEIGHT].chain_tx)
 
         check_dump_output(dump_output)
@@ -500,7 +500,7 @@ def check_dump_output(output):
         dump_output4 = n0.dumptxoutset(path='utxos4.dat', rollback=prev_snap_height)
         assert_equal(
             dump_output4['txoutset_hash'],
-            "45ac2777b6ca96588210e2a4f14b602b41ec37b8b9370673048cc0af434a1ec8")
+            "147d1789e3e29a62e3e15b80078b50603afb5e1e70ea07001c94666afbde38df")
         assert_not_equal(sha256sum_file(dump_output['path']), sha256sum_file(dump_output4['path']))
 
         # Use a hash instead of a height