diff --git a/src/rpc/avalanche.cpp b/src/rpc/avalanche.cpp
--- a/src/rpc/avalanche.cpp
+++ b/src/rpc/avalanche.cpp
@@ -463,7 +463,7 @@
     avalanche::Proof proof;
     bilingual_str error;
     if (!avalanche::Proof::FromHex(proof, request.params[0].get_str(), error)) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, error.original);
+        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, error.original);
     }
 
     NodeContext &node = EnsureNodeContext(request.context);
diff --git a/test/functional/abc_rpc_avalancheproof.py b/test/functional/abc_rpc_avalancheproof.py
--- a/test/functional/abc_rpc_avalancheproof.py
+++ b/test/functional/abc_rpc_avalancheproof.py
@@ -234,10 +234,10 @@
 
         self.log.info("Check the verifyavalancheproof RPC")
 
-        assert_raises_rpc_error(-8, "Proof must be an hexadecimal string",
-                                    node.verifyavalancheproof, "f00")
-        assert_raises_rpc_error(-8, "Proof has invalid format",
-                                    node.verifyavalancheproof, "f00d")
+        assert_raises_rpc_error(-22, "Proof must be an hexadecimal string",
+                                node.verifyavalancheproof, "f00")
+        assert_raises_rpc_error(-22, "Proof has invalid format",
+                                node.verifyavalancheproof, "f00d")
 
         def check_verifyavalancheproof_failure(proof, message):
             assert_raises_rpc_error(-8, "The proof is invalid: " + message,