diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1147,7 +1147,15 @@
         if (!VerifyScript(
                 txin.scriptSig, prevPubKey, 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));
+            }
         }
     }