diff --git a/src/Identity/IdentityServer/RequestValidators/DeviceValidator.cs b/src/Identity/IdentityServer/RequestValidators/DeviceValidator.cs
index 4744f4aca3..36a08326ab 100644
--- a/src/Identity/IdentityServer/RequestValidators/DeviceValidator.cs
+++ b/src/Identity/IdentityServer/RequestValidators/DeviceValidator.cs
@@ -250,21 +250,26 @@ public class DeviceValidator(
         var customResponse = new Dictionary<string, object>();
         switch (errorType)
         {
+            /* 
+             * The ErrorMessage is brittle and is used to control the flow in the clients. Do not change them without updating the client as well.
+             * There is a backwards compatibility issue as well: if you make a change on the clients then ensure that they are backwards
+             * compatible.
+             */
             case DeviceValidationResultType.InvalidUser:
                 result.ErrorDescription = "Invalid user";
-                customResponse.Add("ErrorModel", new ErrorResponseModel("Invalid user."));
+                customResponse.Add("ErrorModel", new ErrorResponseModel("invalid user"));
                 break;
             case DeviceValidationResultType.InvalidNewDeviceOtp:
                 result.ErrorDescription = "Invalid New Device OTP";
-                customResponse.Add("ErrorModel", new ErrorResponseModel("Invalid new device OTP. Try again."));
+                customResponse.Add("ErrorModel", new ErrorResponseModel("invalid new device otp"));
                 break;
             case DeviceValidationResultType.NewDeviceVerificationRequired:
                 result.ErrorDescription = "New device verification required";
-                customResponse.Add("ErrorModel", new ErrorResponseModel("New device verification required."));
+                customResponse.Add("ErrorModel", new ErrorResponseModel("new device verification required"));
                 break;
             case DeviceValidationResultType.NoDeviceInformationProvided:
                 result.ErrorDescription = "No device information provided";
-                customResponse.Add("ErrorModel", new ErrorResponseModel("No device information provided."));
+                customResponse.Add("ErrorModel", new ErrorResponseModel("no device information provided"));
                 break;
         }
         return (result, customResponse);
diff --git a/test/Identity.Test/IdentityServer/DeviceValidatorTests.cs b/test/Identity.Test/IdentityServer/DeviceValidatorTests.cs
index bcb357d640..b71dd6c230 100644
--- a/test/Identity.Test/IdentityServer/DeviceValidatorTests.cs
+++ b/test/Identity.Test/IdentityServer/DeviceValidatorTests.cs
@@ -172,7 +172,7 @@ public class DeviceValidatorTests
 
         Assert.False(result);
         Assert.NotNull(context.CustomResponse["ErrorModel"]);
-        var expectedErrorModel = new ErrorResponseModel("No device information provided.");
+        var expectedErrorModel = new ErrorResponseModel("no device information provided");
         var actualResponse = (ErrorResponseModel)context.CustomResponse["ErrorModel"];
         Assert.Equal(expectedErrorModel.Message, actualResponse.Message);
     }
@@ -418,7 +418,7 @@ public class DeviceValidatorTests
         Assert.False(result);
         Assert.NotNull(context.CustomResponse["ErrorModel"]);
         // PM-13340: The error message should be "invalid user" instead of "no device information provided"
-        var expectedErrorMessage = "No device information provided.";
+        var expectedErrorMessage = "no device information provided";
         var actualResponse = (ErrorResponseModel)context.CustomResponse["ErrorModel"];
         Assert.Equal(expectedErrorMessage, actualResponse.Message);
     }
@@ -552,7 +552,7 @@ public class DeviceValidatorTests
 
         Assert.False(result);
         Assert.NotNull(context.CustomResponse["ErrorModel"]);
-        var expectedErrorMessage = "Invalid new device OTP. Try again.";
+        var expectedErrorMessage = "invalid new device otp";
         var actualResponse = (ErrorResponseModel)context.CustomResponse["ErrorModel"];
         Assert.Equal(expectedErrorMessage, actualResponse.Message);
     }
@@ -604,7 +604,7 @@ public class DeviceValidatorTests
 
         Assert.False(result);
         Assert.NotNull(context.CustomResponse["ErrorModel"]);
-        var expectedErrorMessage = "New device verification required.";
+        var expectedErrorMessage = "new device verification required";
         var actualResponse = (ErrorResponseModel)context.CustomResponse["ErrorModel"];
         Assert.Equal(expectedErrorMessage, actualResponse.Message);
     }