diff --git a/src/rpc/avalanche.cpp b/src/rpc/avalanche.cpp
--- a/src/rpc/avalanche.cpp
+++ b/src/rpc/avalanche.cpp
@@ -93,7 +93,7 @@
     bilingual_str error;
     if (!avalanche::Proof::FromHex(*proof, request.params[2].get_str(),
                                    error)) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, error.original);
+        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, error.original);
     }
 
     if (key != proof->getMaster()) {
diff --git a/test/functional/abc_rpc_addavalanchenode.py b/test/functional/abc_rpc_addavalanchenode.py
--- a/test/functional/abc_rpc_addavalanchenode.py
+++ b/test/functional/abc_rpc_addavalanchenode.py
@@ -58,10 +58,10 @@
             )
 
         self.log.info("Invalid proof")
-        check_addavalanchenode_error(-8,
+        check_addavalanchenode_error(-22,
                                      "Proof must be an hexadecimal string",
                                      proof="not a proof")
-        check_addavalanchenode_error(-8,
+        check_addavalanchenode_error(-22,
                                      "Proof has invalid format",
                                      proof="f000")