wallet (not for backport): improve upgradewallet error messages

Author: jonatack

src/wallet/wallet.cpp

@@ -4111,17 +4111,16 @@ bool CWallet::UpgradeWallet(int version, bilingual_str& error)
     } else {
         WalletLogPrintf("Allowing wallet upgrade up to %i\n", version);
     }
-    if (version < prev_version)
-    {
-        error = _("Cannot downgrade wallet");
+    if (version < prev_version) {
+        error = strprintf(_("Cannot downgrade wallet from version %i to version %i. Wallet version unchanged."), prev_version, version);
         return false;
     }
 
     LOCK(cs_wallet);
 
     // Do not upgrade versions to any version between HD_SPLIT and FEATURE_PRE_SPLIT_KEYPOOL unless already supporting HD_SPLIT
     if (!CanSupportFeature(FEATURE_HD_SPLIT) && version >= FEATURE_HD_SPLIT && version < FEATURE_PRE_SPLIT_KEYPOOL) {
-        error = _("Cannot upgrade a non HD split wallet without upgrading to support pre split keypool. Please use version 169900 or no version specified.");
+        error = strprintf(_("Cannot upgrade a non HD split wallet from version %i to version %i without upgrading to support pre-split keypool. Please use version %i or no version specified."), prev_version, version, FEATURE_PRE_SPLIT_KEYPOOL);
         return false;
     }
 

test/functional/wallet_upgradewallet.py

@@ -211,7 +211,8 @@ def copy_split_hd():
 
         self.log.info('Wallets cannot be downgraded')
         copy_non_hd()
-        self.test_upgradewallet_error(wallet, previous_version=60000, requested_version=40000, msg="Cannot downgrade wallet")
+        self.test_upgradewallet_error(wallet, previous_version=60000, requested_version=40000,
+            msg="Cannot downgrade wallet from version 60000 to version 40000. Wallet version unchanged.")
         wallet.unloadwallet()
         assert_equal(before_checksum, sha256sum_file(node_master_wallet))
         node_master.loadwallet('')
@@ -250,7 +251,8 @@ def copy_split_hd():
         self.log.info('Cannot upgrade to HD Split, needs Pre Split Keypool')
         for version in [139900, 159900, 169899]:
             self.test_upgradewallet_error(wallet, previous_version=130000, requested_version=version,
-                msg="Cannot upgrade a non HD split wallet without upgrading to support pre split keypool. Please use version 169900 or no version specified.")
+                msg="Cannot upgrade a non HD split wallet from version {} to version {} without upgrading to "
+                    "support pre-split keypool. Please use version 169900 or no version specified.".format(130000, version))
 
         self.log.info('Upgrade HD to HD chain split')
         self.test_upgradewallet(wallet, previous_version=130000, requested_version=169900)