diff --git a/com/Unit/_errors.lua b/com/Unit/_errors.lua
new file mode 100644
index 0000000..1fd6900
--- /dev/null
+++ b/com/Unit/_errors.lua
@@ -0,0 +1,30 @@
+-- File com/Unit/_errors.lua
+--
+-- Created at 2025-10-10
+-- Description:
+--- Centralized error definitions for Unit operations
+--- to keep API responses consistent and clean.
+
+local errors = {
+  -- Common validation
+  MISSING_PARAMS = { code = -32602, message = "Missing params" },
+  INVALID_FIELD_TYPE = { code = -32602, message = "'fields' must be a non-empty table" },
+  INVALID_BY_PARAM = { code = -32602, message = "Invalid 'by' param" },
+  NO_VALID_FIELDS = { code = -32604, message = "No valid fields to update" },
+
+  -- Existence / duplication
+  UNIT_NOT_FOUND = { code = -32102, message = "Unit is not exists" },
+  UNIT_EXISTS = { code = -32101, message = "Unit is already exists" },
+
+  -- Database & constraint
+  UNIQUE_CONSTRAINT = { code = -32602, message = "Unique constraint failed" },
+  DB_QUERY_FAILED = { code = -32001, message = "Database query failed" },
+  DB_EXEC_FAILED = { code = -32002, message = "Database execution failed" },
+  DB_INSERT_FAILED = { code = -32003, message = "Failed to create unit" },
+  DB_DELETE_FAILED = { code = -32004, message = "Failed to delete unit" },
+
+  -- Generic fallback
+  UNKNOWN = { code = -32099, message = "Unexpected internal error" },
+}
+
+return errors