diff --git a/src/Neo/Wallets/Helper.cs b/src/Neo/Wallets/Helper.cs
index b8427d078d..5beae49ab9 100644
--- a/src/Neo/Wallets/Helper.cs
+++ b/src/Neo/Wallets/Helper.cs
@@ -119,7 +119,8 @@ public static long CalculateNetworkFee(this Transaction tx, DataCache snapshot,
                 {
                     var contract = NativeContract.ContractManagement.GetContract(snapshot, hash);
                     if (contract is null)
-                        throw new ArgumentException($"The smart contract or address {hash} is not found");
+                        throw new ArgumentException($"The smart contract or address {hash} ({hash.ToAddress(settings.AddressVersion)}) is not found. " +
+                            $"If this is your wallet address and you want to sign a transaction with it, make sure you have opened this wallet.");
                     var md = contract.Manifest.Abi.GetMethod(ContractBasicMethod.Verify, ContractBasicMethod.VerifyPCount);
                     if (md is null)
                         throw new ArgumentException($"The smart contract {contract.Hash} haven't got verify method");
diff --git a/tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.SmartContract.cs b/tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.SmartContract.cs
index f994137258..9a8b87da9a 100644
--- a/tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.SmartContract.cs
+++ b/tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.SmartContract.cs
@@ -102,7 +102,8 @@ public void TestInvokeFunction()
         Assert.AreEqual(resp["diagnostics"]["invokedcontracts"]["call"][0]["hash"], NeoToken.NEO.Hash.ToString());
         Assert.IsTrue(((JArray)resp["diagnostics"]["storagechanges"]).Count == 4);
         Assert.AreEqual(resp["state"], nameof(VM.VMState.HALT));
-        Assert.AreEqual(resp["exception"], $"The smart contract or address {MultisigScriptHash.ToString()} is not found");
+        Assert.AreEqual(resp["exception"], $"The smart contract or address {MultisigScriptHash} ({MultisigAddress}) is not found. " +
+                            $"If this is your wallet address and you want to sign a transaction with it, make sure you have opened this wallet.");
         JArray notifications = (JArray)resp["notifications"];
         Assert.AreEqual(notifications.Count, 2);
         Assert.AreEqual(notifications[0]["eventname"].AsString(), "Transfer");