bitcoin-core-ipc-extranonce.patch

diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index 84fd5bb794..6fc664174b 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -988,10 +988,16 @@ public:
             // Also wait during the final catch-up moments after IBD.
             if (!CooldownIfHeadersAhead(chainman(), notifications(), *maybe_tip, m_interrupt_mining)) return {};
         }
 
         BlockAssembler::Options assemble_options{options};
+        // At heights <= 16 the BIP34 height push is only 1 byte, but consensus
+        // requires coinbase scriptSig to be >= 2 bytes (bad-cb-length). Pad with
+        // a dummy OP_0 extranonce so createNewBlock succeeds at these heights.
+        if (WITH_LOCK(chainman().GetMutex(), return chainman().ActiveChain().Height()) < 16) {
+            assemble_options.include_dummy_extranonce = true;
+        }
         ApplyArgsManOptions(*Assert(m_node.args), assemble_options);
         return std::make_unique<BlockTemplateImpl>(assemble_options, BlockAssembler{chainman().ActiveChainstate(), context()->mempool.get(), assemble_options}.CreateNewBlock(), m_node);
     }
 
     void interrupt() override