From ec4c79326bb670c2cc1757ecfb1900f8460c5257 Mon Sep 17 00:00:00 2001
From: Anthony Towns <aj@erisian.com.au>
Date: Thu, 20 Jun 2019 19:40:29 +1000
Subject: [PATCH] signrawtransaction*: improve error for partial signing

Thanks to Danial Jaffy (tipu) for reporting this issue.
---
 src/rpc/rawtransaction_util.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/rpc/rawtransaction_util.cpp b/src/rpc/rawtransaction_util.cpp
index e05f28347..f1d176ba4 100644
--- a/src/rpc/rawtransaction_util.cpp
+++ b/src/rpc/rawtransaction_util.cpp
@@ -309,6 +309,9 @@ UniValue SignTransaction(CMutableTransaction& mtx, const SigningProvider* keysto
             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 if (serror == SCRIPT_ERR_SIG_NULLFAIL) {
+                // Verification failed (possibly due to insufficient signatures).
+                TxInErrorToJSON(txin, vErrors, "CHECK(MULTI)SIG failing with non-zero signature (possibly need more signatures)");
             } else {
                 TxInErrorToJSON(txin, vErrors, ScriptErrorString(serror));
             }