From f7aef8d331decc871108e50890567c5bc7967b1e Mon Sep 17 00:00:00 2001
From: Kittywhiskers Van Gogh <63189531+kwvg@users.noreply.github.com>
Date: Wed, 18 Aug 2021 14:36:28 -0400
Subject: [PATCH] init: Delay RPC block notif until warmup finished

---
 src/init.cpp            | 10 ++++++++++
 src/node/chainstate.cpp |  2 --
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/init.cpp b/src/init.cpp
index f6e4de9e55..eb4fd0d685 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -2400,7 +2400,17 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
 
     // ********************************************************* Step 13: finished
 
+    // At this point, the RPC is "started", but still in warmup, which means it
+    // cannot yet be called. Before we make it callable, we need to make sure
+    // that the RPC's view of the best block is valid and consistent with
+    // ChainstateManager's ActiveTip.
+    //
+    // If we do not do this, RPC's view of the best block will be height=0 and
+    // hash=0x0. This will lead to erroroneous responses for things like
+    // waitforblockheight.
+    RPCNotifyBlockChange(chainman.ActiveTip());
     SetRPCWarmupFinished();
+
     uiInterface.InitMessage(_("Done loading").translated);
 
     for (const auto& client : node.chain_clients) {
diff --git a/src/node/chainstate.cpp b/src/node/chainstate.cpp
index 88cb8add95..59a91679ef 100644
--- a/src/node/chainstate.cpp
+++ b/src/node/chainstate.cpp
@@ -6,7 +6,6 @@
 
 #include <chainparams.h> // for CChainParams
 #include <deploymentstatus.h> // for DeploymentActiveAfter
-#include <rpc/blockchain.h> // for RPCNotifyBlockChange
 #include <util/time.h> // for GetTime
 #include <node/blockstorage.h> // for CleanupBlockRevFiles, fHavePruned, fReindex
 #include <shutdown.h> // for ShutdownRequested
@@ -246,7 +245,6 @@ std::optional<ChainstateLoadVerifyError> VerifyLoadedChainstate(ChainstateManage
         for (CChainState* chainstate : chainman.GetAll()) {
             if (!is_coinsview_empty(chainstate)) {
                 const CBlockIndex* tip = chainstate->m_chain.Tip();
-                RPCNotifyBlockChange(tip);
                 if (tip && tip->nTime > GetTime() + MAX_FUTURE_BLOCK_TIME) {
                     return ChainstateLoadVerifyError::ERROR_BLOCK_FROM_FUTURE;
                 }