diff --git a/src/Dexorder.sol b/src/Dexorder.sol
index ec32236..d02b150 100644
--- a/src/Dexorder.sol
+++ b/src/Dexorder.sol
@@ -7,7 +7,7 @@ pragma abicoder v2;
 contract Dexorder {
     // represents the Dexorder organization
 
-    event DexorderExecutions(uint128 indexed id, bytes[] errors);
+    event DexorderExecutions(bytes16 indexed id, string[] errors);
 
     struct ExecutionRequest {
         address payable vault;
@@ -17,29 +17,29 @@ contract Dexorder {
     }
 
 
-    function execute( uint128 id, ExecutionRequest memory req ) public returns (bytes memory error) {
+    function execute( bytes16 id, ExecutionRequest memory req ) public returns (string memory error) {
         error = _execute(req);
-        bytes[] memory errors = new bytes[](1);
+        string[] memory errors = new string[](1);
         errors[0] = error;
         emit DexorderExecutions(id, errors);
     }
 
 
-    function execute( uint128 id, ExecutionRequest[] memory reqs ) public returns (bytes[] memory errors) {
-        errors = new bytes[](reqs.length);
+    function execute( bytes16 id, ExecutionRequest[] memory reqs ) public returns (string[] memory errors) {
+        errors = new string[](reqs.length);
         for( uint8 i=0; i<reqs.length; i++ )
             errors[i] = _execute(reqs[i]);
         emit DexorderExecutions(id, errors);
     }
 
 
-    function _execute( ExecutionRequest memory req ) private returns (bytes memory error) {
+    function _execute( ExecutionRequest memory req ) private returns (string memory error) {
         // single tranche execution
         try Vault(req.vault).execute(req.orderIndex, req.trancheIndex, req.proof) {
-            return '';
+            error = '';
         }
-        catch (bytes memory reason) {
-            return reason;
+        catch Error(string memory reason) {
+            error = reason;
         }
     }
 }
diff --git a/src/VaultAddress.sol b/src/VaultAddress.sol
index 2591884..80ac766 100644
--- a/src/VaultAddress.sol
+++ b/src/VaultAddress.sol
@@ -10,7 +10,7 @@ library VaultAddress {
     // keccak-256 hash of the Vault's bytecode (not the deployed bytecode but the initialization bytecode)
     // can paste into:
     // https://emn178.github.io/online-tools/keccak_256.html
-    bytes32 internal constant VAULT_INIT_CODE_HASH = 0x94dd1e2fe4a67770f9295aff1b352fb0792647d2377cd96aa72e4c3a3222aad1;
+    bytes32 internal constant VAULT_INIT_CODE_HASH = 0xbf7fa358e7e01c60966db5f8298feffb8b7e2aa494a6ba4a0f94a17a817f93ff;
 
     // the contract being constructed must not have any constructor arguments or the determinism will be broken.  instead, use a callback to
     // get construction arguments