From df10edfd03fe4c9d1eca43a17ac4c54a14ac4832 Mon Sep 17 00:00:00 2001
From: MeshCollider <dobsonsa68@gmail.com>
Date: Sat, 9 Sep 2017 00:20:00 +1200
Subject: [PATCH] More user-friendly error message when partially signing

---
 src/rpc/rawtransaction.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index a0322f67b407e..b2fc6a357a595 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -873,7 +873,12 @@ UniValue signrawtransaction(const JSONRPCRequest& request)
 
         ScriptError serror = SCRIPT_ERR_OK;
         if (!VerifyScript(txin.scriptSig, prevPubKey, &txin.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, TransactionSignatureChecker(&txConst, i, amount), &serror)) {
-            TxInErrorToJSON(txin, vErrors, ScriptErrorString(serror));
+            if (serror == SCRIPT_ERR_INVALID_STACK_OPERATION) {
+                // Unable to sign input and verification failed (possible attempt to partially sign).
+                TxInErrorToJSON(txin, vErrors, "Unable to sign input, invalid stack size (possibly missing key)");
+            } else {
+                TxInErrorToJSON(txin, vErrors, ScriptErrorString(serror));
+            }
         }
     }
     bool fComplete = vErrors.empty();