Bump wallet version for pre split keypool

Bump the wallet version to indicate support for the pre split keypool.
Also prevents any wallets from upgrading to versions between HD_SPLIT
and PRE_SPLIT_KEYPOOL.

src/wallet/wallet.cpp

@@ -4060,6 +4060,14 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
     // Upgrade to HD if explicit upgrade
     if (gArgs.GetBoolArg("-upgradewallet", false)) {
         LOCK(walletInstance->cs_wallet);
+
+        // Do not upgrade versions to any version between HD_SPLIT and FEATURE_PRE_SPLIT_KEYPOOL unless already supporting HD_SPLIT
+        int max_version = walletInstance->nWalletVersion;
+        if (!walletInstance->CanSupportFeature(FEATURE_HD_SPLIT) && max_version >=FEATURE_HD_SPLIT && max_version < FEATURE_PRE_SPLIT_KEYPOOL) {
+            InitError(_("Cannot upgrade a non HD split wallet without upgrading to support pre split keypool. Please use -upgradewallet=169900 or -upgradewallet with no version specified."));
+            return nullptr;
+        }
+
         bool hd_upgrade = false;
         bool split_upgrade = false;
         if (walletInstance->CanSupportFeature(FEATURE_HD) && !walletInstance->IsHDEnabled()) {
@@ -4076,7 +4084,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
         // Upgrade to HD chain split if necessary
         if (walletInstance->CanSupportFeature(FEATURE_HD_SPLIT)) {
             LogPrintf("Upgrading wallet to use HD chain split\n");
-            walletInstance->SetMinVersion(FEATURE_HD_SPLIT);
+            walletInstance->SetMinVersion(FEATURE_PRE_SPLIT_KEYPOOL);
             split_upgrade = FEATURE_HD_SPLIT > prev_version;
         }
         // Mark all keys currently in the keypool as pre-split

src/wallet/wallet.h

@@ -89,7 +89,9 @@ enum WalletFeature
 
     FEATURE_NO_DEFAULT_KEY = 159900, // Wallet without a default key written
 
-    FEATURE_LATEST = FEATURE_NO_DEFAULT_KEY
+    FEATURE_PRE_SPLIT_KEYPOOL = 169900, // Upgraded to HD SPLIT and can have a pre-split keypool
+
+    FEATURE_LATEST = FEATURE_PRE_SPLIT_KEYPOOL
 };
 
 enum class OutputType {