diff --git a/Controllers/InstructorsDataController.cs b/Controllers/InstructorsDataController.cs
index 3f5db8a..6ec9a6a 100644
--- a/Controllers/InstructorsDataController.cs
+++ b/Controllers/InstructorsDataController.cs
@@ -31,18 +31,21 @@ namespace InstructorsListApp.Controllers
                 databaseContext.Entry<Instructor>(instructor).State = EntityState.Detached; // remove unneccessary refs
                 return Ok(instructor);
             }
-            return NotFound("Given instructor isn't found");
+            return NotFound(new Error(Error.EntryIsNotFound, "No such instructor"));
         }
 
         [HttpPost("add")]
         public IActionResult CreateInstructorEntry([FromBody] Instructor instructor) {
             if(ModelState.IsValid) {
+                if(instructor.FirstName == null && instructor.LastName == null && instructor.MiddleName == null) {
+                    return BadRequest(new Error(Error.PostBodyIsNotValid, "Given model isn't valid!"));
+                }
                 instructor.Id = Guid.NewGuid().ToString();
                 databaseContext.Instructors.Add(instructor);
                 databaseContext.SaveChanges();
                 return Ok(instructor.Id);
             }
-            return BadRequest(ModelState);
+            return BadRequest(new Error(Error.PostBodyIsNotValid, "Given model isn't valid!"));
         }
 
         [HttpPut("{id}")]
@@ -56,7 +59,7 @@ namespace InstructorsListApp.Controllers
                     databaseContext.SaveChanges();
                     return Ok();
                 }
-                return NotFound("Given instructor isn't found");
+                return NotFound(new Error(Error.EntryIsNotFound, "No such instructor"));
             }
             return BadRequest(ModelState);
         }
@@ -69,7 +72,7 @@ namespace InstructorsListApp.Controllers
                 databaseContext.SaveChanges();
                 return Ok();
             }
-            return NotFound("No such instructor");
+            return NotFound(new Error(Error.EntryIsNotFound, "No such instructor"));
         }
     }
 }
diff --git a/Models/Error.cs b/Models/Error.cs
new file mode 100644
index 0000000..05b4e8e
--- /dev/null
+++ b/Models/Error.cs
@@ -0,0 +1,14 @@
+namespace InstructorsListApp.Models {
+    public class Error {
+        public static int EntryIsNotFound = 0x0;
+        public static int PostBodyIsNotValid = 0x1;
+
+        public int errCode {get; set;}
+        public string errText {get; set;}
+
+        public Error(int errCode, string errText) {
+            this.errCode = errCode;
+            this.errText = errText;
+        }
+    }
+}
\ No newline at end of file
diff --git a/Models/Instructor.cs b/Models/Instructor.cs
index d944063..7a4bc8d 100644
--- a/Models/Instructor.cs
+++ b/Models/Instructor.cs
@@ -1,8 +1,8 @@
 namespace InstructorsListApp.Models {
     public class Instructor {
-    public string Id {get; set;}
-    public string FirstName {get;set;}
-    public string MiddleName {get;set;}
-    public string LastName {get;set;}
-}
+        public string Id {get; set;}
+        public string FirstName {get;set;}
+        public string MiddleName {get;set;}
+        public string LastName {get;set;}
+    }
 }
\ No newline at end of file