If an action fails, print out its name as well as the error code. Use

dlls/msi/action.c

@@ -762,7 +762,7 @@ static UINT ITERATE_Actions(MSIRECORD *row, LPVOID param)
         rc = ERROR_SUCCESS;
 
     if (rc != ERROR_SUCCESS)
-        ERR("Execution halted due to error (%i)\n",rc);
+        ERR("Execution halted, action %s returned %i\n", debugstr_w(action), rc);
 
     return rc;
 }

dlls/msi/custom.c

@@ -335,7 +335,7 @@ static UINT process_action_return_value(UINT type, HANDLE ThreadHandle)
     case ERROR_NO_MORE_ITEMS:
         return ERROR_SUCCESS;
     default:
-            ERR("Invalid Return Code %lx\n",rc);
+        ERR("Invalid Return Code %ld\n",rc);
         return ERROR_INSTALL_FAILURE;
     }
 }