rpc, cli: improve error message on multiwallet mode

The primary objective is to provide users with clearer
and more informative error messages when encountering
the RPC_WALLET_NOT_SPECIFIED error, which occurs when
multiple wallets are loadad.

This commit also rectifies the error message consistency
by bringing the error message in line with the definition
established in protocol.h ("error when there are multiple
wallets loaded").

2 files changed, 12 insertions, 3 deletions

diff --git a/test/functional/interface_bitcoin_cli.py b/test/functional/interface_bitcoin_cli.py
index 30bf97185a..7194c8ece4 100755
--- a/test/functional/interface_bitcoin_cli.py
+++ b/test/functional/interface_bitcoin_cli.py
@@ -30,7 +30,12 @@ JSON_PARSING_ERROR = 'error: Error parsing JSON: foo'
 BLOCKS_VALUE_OF_ZERO = 'error: the first argument (number of blocks to generate, default: 1) must be an integer value greater than zero'
 TOO_MANY_ARGS = 'error: too many arguments (maximum 2 for nblocks and maxtries)'
 WALLET_NOT_LOADED = 'Requested wallet does not exist or is not loaded'
-WALLET_NOT_SPECIFIED = 'Wallet file not specified'
+WALLET_NOT_SPECIFIED = (
+    "Multiple wallets are loaded. Please select which wallet to use by requesting the RPC "
+    "through the /wallet/<walletname> URI path. Or for the CLI, specify the \"-rpcwallet=<walletname>\" "
+    "option before the command (run \"bitcoin-cli -h\" for help or \"bitcoin-cli listwallets\" to see "
+    "which wallets are currently loaded)."
+)
 
 
 def cli_get_info_string_to_dict(cli_get_info_string):
@@ -331,6 +336,10 @@ class TestBitcoinCli(BitcoinTestFramework):
             n4 = 10
             blocks = self.nodes[0].getblockcount()
 
+            self.log.info('Test -generate -rpcwallet=<filename> raise RPC error')
+            wallet2_path = f'-rpcwallet={self.nodes[0].wallets_path / wallets[2] / self.wallet_data_filename}'
+            assert_raises_rpc_error(-18, WALLET_NOT_LOADED, self.nodes[0].cli(wallet2_path, '-generate').echo)
+
             self.log.info('Test -generate -rpcwallet with no args')
             generate = self.nodes[0].cli(rpcwallet2, '-generate').send_cli()
             assert_equal(set(generate.keys()), {'address', 'blocks'})
diff --git a/test/functional/wallet_multiwallet.py b/test/functional/wallet_multiwallet.py
index 156f4279b4..149b1246d8 100755
--- a/test/functional/wallet_multiwallet.py
+++ b/test/functional/wallet_multiwallet.py
@@ -229,7 +229,7 @@ class MultiWalletTest(BitcoinTestFramework):
         assert_raises_rpc_error(-18, "Requested wallet does not exist or is not loaded", wallet_bad.getwalletinfo)
 
         # accessing wallet RPC without using wallet endpoint fails
-        assert_raises_rpc_error(-19, "Wallet file not specified", node.getwalletinfo)
+        assert_raises_rpc_error(-19, "Multiple wallets are loaded. Please select which wallet", node.getwalletinfo)
 
         w1, w2, w3, w4, *_ = wallets
         self.generatetoaddress(node, nblocks=COINBASE_MATURITY + 1, address=w1.getnewaddress(), sync_fun=self.no_op)
@@ -275,7 +275,7 @@ class MultiWalletTest(BitcoinTestFramework):
         loadwallet_name = node.loadwallet(wallet_names[1])
         assert_equal(loadwallet_name['name'], wallet_names[1])
         assert_equal(node.listwallets(), wallet_names[0:2])
-        assert_raises_rpc_error(-19, "Wallet file not specified", node.getwalletinfo)
+        assert_raises_rpc_error(-19, "Multiple wallets are loaded. Please select which wallet", node.getwalletinfo)
         w2 = node.get_wallet_rpc(wallet_names[1])
         w2.getwalletinfo()