diff --git a/src/Altinn.App.Api/Controllers/ActionsController.cs b/src/Altinn.App.Api/Controllers/ActionsController.cs
index 2786ee59b..a31b92941 100644
--- a/src/Altinn.App.Api/Controllers/ActionsController.cs
+++ b/src/Altinn.App.Api/Controllers/ActionsController.cs
@@ -213,10 +213,9 @@ await Task.WhenAll(
         );
         await saveTask;
 
-        var updatedDataModels = changes.FormDataChanges.ToDictionary(
-            c => c.DataElementIdentifier.Id,
-            c => c.CurrentFormData
-        );
+        var updatedDataModels = changes
+            .FormDataChanges.Where(c => c.Type != ChangeType.Deleted)
+            .ToDictionary(c => c.DataElementIdentifier.Id, c => c.CurrentFormData);
 
         return Ok(
             new UserActionResponse()
diff --git a/src/Altinn.App.Core/Internal/Data/InstanceDataUnitOfWork.cs b/src/Altinn.App.Core/Internal/Data/InstanceDataUnitOfWork.cs
index 36744dacf..cab697cc2 100644
--- a/src/Altinn.App.Core/Internal/Data/InstanceDataUnitOfWork.cs
+++ b/src/Altinn.App.Core/Internal/Data/InstanceDataUnitOfWork.cs
@@ -147,7 +147,7 @@ public FormDataChange AddFormDataElement(string dataTypeId, object model)
         if (modelType.FullName != classRef)
         {
             throw new InvalidOperationException(
-                $"Data object registered for {dataTypeId} is not of type {classRef} as specified in application metadata"
+                $"Tried to save {modelType.FullName} as {dataTypeId}, but applicationmetadata.json specifies {classRef}"
             );
         }
 
diff --git a/src/Altinn.App.Core/Models/UserAction/UserActionContext.cs b/src/Altinn.App.Core/Models/UserAction/UserActionContext.cs
index d2caf7c64..441548ab7 100644
--- a/src/Altinn.App.Core/Models/UserAction/UserActionContext.cs
+++ b/src/Altinn.App.Core/Models/UserAction/UserActionContext.cs
@@ -66,7 +66,7 @@ public UserActionContext(
     /// <summary>
     /// Access dataElements through this accessor to ensure that changes gets saved in storage and returned to frontend
     /// </summary>
-    public IInstanceDataAccessor DataMutator { get; }
+    public IInstanceDataMutator DataMutator { get; }
 
     /// <summary>
     /// The user performing the action
diff --git a/test/Altinn.App.Api.Tests/Controllers/ActionsControllerTests.cs b/test/Altinn.App.Api.Tests/Controllers/ActionsControllerTests.cs
index 28a18fd44..1ed3f22e7 100644
--- a/test/Altinn.App.Api.Tests/Controllers/ActionsControllerTests.cs
+++ b/test/Altinn.App.Api.Tests/Controllers/ActionsControllerTests.cs
@@ -1,16 +1,20 @@
 using System.Net;
 using System.Net.Http.Headers;
+using System.Net.Http.Json;
 using System.Text;
 using System.Text.Json;
 using Altinn.App.Api.Models;
 using Altinn.App.Api.Tests.Data;
+using Altinn.App.Api.Tests.Data.apps.tdd.task_action.config.models;
 using Altinn.App.Api.Tests.Utils;
 using Altinn.App.Core.Features;
+using Altinn.App.Core.Internal.Data;
 using Altinn.App.Core.Models.Process;
 using Altinn.App.Core.Models.UserAction;
 using FluentAssertions;
 using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using Xunit.Abstractions;
 
 namespace Altinn.App.Api.Tests.Controllers;
@@ -35,7 +39,6 @@ public async Task Perform_returns_403_if_user_not_authorized()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(1000, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -61,7 +64,6 @@ public async Task Perform_returns_401_if_user_not_authenticated()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         using var content = new StringContent(
             "{\"action\":\"lookup_unauthorized\"}",
@@ -85,7 +87,6 @@ public async Task Perform_returns_401_if_userId_is_null()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(null, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -111,7 +112,6 @@ public async Task Perform_returns_400_if_action_is_null()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(1000, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -133,7 +133,6 @@ public async Task Perform_returns_409_if_process_not_started()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef43");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(1000, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -155,7 +154,6 @@ public async Task Perform_returns_409_if_process_ended()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef42");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(1000, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -181,7 +179,6 @@ public async Task Perform_returns_200_if_action_succeeded()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(1000, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -234,7 +231,6 @@ public async Task Perform_returns_400_if_action_failed_and_errorType_is_BadReque
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(400, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -260,7 +256,6 @@ public async Task Perform_returns_401_if_action_failed_and_errorType_is_Unauthor
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(401, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -286,7 +281,6 @@ public async Task Perform_returns_409_if_action_failed_and_errorType_is_Conflict
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(409, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -312,7 +306,6 @@ public async Task Perform_returns_500_if_action_failed_and_errorType_is_Internal
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(500, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -338,7 +331,6 @@ public async Task Perform_returns_404_if_action_implementation_not_found()
         var app = "task-action";
         HttpClient client = GetRootedClient(org, app);
         Guid guid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
         string token = PrincipalUtil.GetToken(1001, null, 3);
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -353,6 +345,197 @@ public async Task Perform_returns_404_if_action_implementation_not_found()
         response.StatusCode.Should().Be(HttpStatusCode.NotFound);
     }
 
+    [Fact]
+    public async Task PerformFillActionThatMutatesData()
+    {
+        var org = "tdd";
+        var app = "task-action";
+        Guid instanceGuid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
+        int instanceOwner = 1337;
+        TestData.PrepareInstance(org, app, 1337, instanceGuid);
+        OverrideServicesForThisTest = (services) =>
+        {
+            services.AddTransient<IUserAction, FillAction>();
+        };
+        var client = GetRootedClient(org, app, 1337, null);
+        string token = PrincipalUtil.GetToken(1001, null, 3);
+        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
+
+        // Run buttonId "add"
+        using var content = JsonContent.Create(new { action = "fill", buttonId = "add" });
+        using HttpResponseMessage addResponse = await client.PostAsync(
+            $"/{org}/{app}/instances/{instanceOwner}/{instanceGuid}/actions",
+            content
+        );
+
+        var parsedAddResponse = await VerifyStatusAndDeserialize<UserActionResponse>(addResponse, HttpStatusCode.OK);
+        parsedAddResponse.ClientActions.Should().BeEmpty();
+        parsedAddResponse.Instance.Should().NotBeNull();
+        parsedAddResponse.Instance.Id.Should().Be($"{instanceOwner}/{instanceGuid}");
+        var dataElement = parsedAddResponse.Instance.Data.Should().ContainSingle().Which;
+
+        var schemeElement = parsedAddResponse
+            .UpdatedDataModels.Should()
+            .HaveCount(1)
+            .And.ContainKey(dataElement.Id)
+            .WhoseValue.Should()
+            .BeOfType<JsonElement>()
+            .Which;
+        var scheme =
+            schemeElement.Deserialize<Scheme>(_jsonSerializerOptions)
+            ?? throw new Exception("Failed to deserialize Scheme");
+        scheme.TestCustomButtonInput.Should().Be("Hello a");
+
+        // Run buttonId "update"
+        using var updateContent = JsonContent.Create(new { action = "fill", buttonId = "update" });
+        using HttpResponseMessage updateResponse = await client.PostAsync(
+            $"/{org}/{app}/instances/{instanceOwner}/{instanceGuid}/actions",
+            updateContent
+        );
+        var parsedUpdateResponse = await VerifyStatusAndDeserialize<UserActionResponse>(
+            updateResponse,
+            HttpStatusCode.OK
+        );
+        parsedUpdateResponse.ClientActions.Should().BeEmpty();
+        parsedUpdateResponse.Instance.Should().NotBeNull();
+        parsedUpdateResponse.Instance.Id.Should().Be($"{instanceOwner}/{instanceGuid}");
+        var updatedDataElement = parsedUpdateResponse.Instance.Data.Should().ContainSingle().Which;
+        var updatedSchemeElement = parsedUpdateResponse
+            .UpdatedDataModels.Should()
+            .HaveCount(1)
+            .And.ContainKey(updatedDataElement.Id)
+            .WhoseValue.Should()
+            .BeOfType<JsonElement>()
+            .Which;
+        var updatedScheme =
+            updatedSchemeElement.Deserialize<Scheme>(_jsonSerializerOptions)
+            ?? throw new Exception("Failed to deserialize Scheme");
+        updatedScheme.TestCustomButtonInput.Should().Be("Hello a");
+        updatedScheme.TestCustomButtonReadOnlyInput.Should().Be("Her kommer det data fra backend");
+
+        TestData
+            .GetDataElementBlobContnet(org, app, instanceOwner, instanceGuid, Guid.Parse(updatedDataElement.Id))
+            .Should()
+            .Contain("Her kommer det data fra backend");
+
+        // Run buttonId "updateObsolete"
+        using var updateObsoleteContent = JsonContent.Create(new { action = "fill", buttonId = "updateObsolete" });
+        using HttpResponseMessage updateObsoleteResponse = await client.PostAsync(
+            $"/{org}/{app}/instances/{instanceOwner}/{instanceGuid}/actions",
+            updateObsoleteContent
+        );
+        var parsedUpdateObsoleteResponse = await VerifyStatusAndDeserialize<UserActionResponse>(
+            updateObsoleteResponse,
+            HttpStatusCode.OK
+        );
+        parsedUpdateObsoleteResponse.ClientActions.Should().BeEmpty();
+        parsedUpdateObsoleteResponse.Instance.Should().NotBeNull();
+        parsedUpdateObsoleteResponse.Instance.Id.Should().Be($"{instanceOwner}/{instanceGuid}");
+        var updatedObsoleteDataElement = parsedUpdateObsoleteResponse.Instance.Data.Should().ContainSingle().Which;
+        var updatedObsoleteSchemeElement = parsedUpdateObsoleteResponse
+            .UpdatedDataModels.Should()
+            .HaveCount(1)
+            .And.ContainKey(updatedObsoleteDataElement.Id)
+            .WhoseValue.Should()
+            .BeOfType<JsonElement>()
+            .Which;
+        var updatedObsoleteScheme =
+            updatedObsoleteSchemeElement.Deserialize<Scheme>(_jsonSerializerOptions)
+            ?? throw new Exception("Failed to deserialize Scheme");
+        updatedObsoleteScheme.description.Should().Be("Obsolete data");
+
+        TestData
+            .GetDataElementBlobContnet(org, app, instanceOwner, instanceGuid, Guid.Parse(updatedDataElement.Id))
+            .Should()
+            .Contain("Obsolete data");
+
+        // Run buttonId "delete"
+        using var deleteContent = JsonContent.Create(new { action = "fill", buttonId = "delete" });
+        using HttpResponseMessage deleteResponse = await client.PostAsync(
+            $"/{org}/{app}/instances/{instanceOwner}/{instanceGuid}/actions",
+            deleteContent
+        );
+        var parsedDeleteResponse = await VerifyStatusAndDeserialize<UserActionResponse>(
+            deleteResponse,
+            HttpStatusCode.OK
+        );
+        parsedDeleteResponse.ClientActions.Should().BeEmpty();
+        parsedDeleteResponse.Instance.Should().NotBeNull();
+        parsedDeleteResponse.Instance.Id.Should().Be($"{instanceOwner}/{instanceGuid}");
+        parsedDeleteResponse.Instance.Data.Should().BeEmpty();
+        parsedDeleteResponse.UpdatedDataModels.Should().BeEmpty();
+
+        // Cleanup testdata
+        TestData.DeleteInstanceAndData(org, app, instanceOwner, instanceGuid);
+    }
+
+    [Fact]
+    public async Task PerformFillAction_GetClientActions()
+    {
+        var org = "tdd";
+        var app = "task-action";
+        Guid instanceGuid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
+        int instanceOwner = 1337;
+        TestData.PrepareInstance(org, app, 1337, instanceGuid);
+        OverrideServicesForThisTest = (services) =>
+        {
+            services.AddTransient<IUserAction, FillAction>();
+        };
+        var client = GetRootedClient(org, app, 1337, null);
+        string token = PrincipalUtil.GetToken(1001, null, 3);
+        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
+
+        // run buttonId "getClientActions"
+        using var getClientActionsContent = JsonContent.Create(new { action = "fill", buttonId = "getClientActions" });
+        using HttpResponseMessage getClientActionsResponse = await client.PostAsync(
+            $"/{org}/{app}/instances/{instanceOwner}/{instanceGuid}/actions",
+            getClientActionsContent
+        );
+        var parsedGetClientActionsResponse = await VerifyStatusAndDeserialize<UserActionResponse>(
+            getClientActionsResponse,
+            HttpStatusCode.OK
+        );
+        parsedGetClientActionsResponse.ClientActions.Should().ContainSingle().Which.Id.Should().Be("nextPage");
+
+        // Cleanup testdata
+        TestData.DeleteInstanceAndData(org, app, instanceOwner, instanceGuid);
+    }
+
+    [Fact]
+    public async Task PerformFillAction_Fail()
+    {
+        var org = "tdd";
+        var app = "task-action";
+        Guid instanceGuid = new Guid("b1135209-628e-4a6e-9efd-e4282068ef41");
+        int instanceOwner = 1337;
+        TestData.PrepareInstance(org, app, 1337, instanceGuid);
+        OverrideServicesForThisTest = (services) =>
+        {
+            services.AddTransient<IUserAction, FillAction>();
+        };
+        var client = GetRootedClient(org, app, 1337, null);
+        string token = PrincipalUtil.GetToken(1001, null, 3);
+        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
+
+        // Run buttonId "fail"
+        using var failContent = JsonContent.Create(new { action = "fill", buttonId = "fail" });
+        using HttpResponseMessage failResponse = await client.PostAsync(
+            $"/{org}/{app}/instances/{instanceOwner}/{instanceGuid}/actions",
+            failContent
+        );
+        var parsedFailResponse = await VerifyStatusAndDeserialize<UserActionResponse>(
+            failResponse,
+            HttpStatusCode.Conflict
+        );
+        parsedFailResponse.ClientActions.Should().ContainSingle().Which.Id.Should().Be("nextPage");
+        parsedFailResponse.Error.Should().NotBeNull();
+        parsedFailResponse.Error!.Code.Should().Be("machine-readable-error-code");
+        parsedFailResponse.Error!.Message.Should().Be("Her kommer det en feilmelding");
+
+        // Cleanup testdata
+        TestData.DeleteInstanceAndData(org, app, instanceOwner, instanceGuid);
+    }
+
     //TODO: replace this assertion with a proper one once fluentassertions has a json compare feature scheduled for v7 https://github.com/fluentassertions/fluentassertions/issues/2205
     private void CompareResult<T>(string expectedString, string actualString, Action<T?>? mutator = null)
     {
@@ -366,6 +549,88 @@ private void CompareResult<T>(string expectedString, string actualString, Action
     }
 }
 
+public class FillAction : IUserAction
+{
+    private readonly ILogger<FillAction> _logger;
+    private readonly IDataClient _dataClient;
+
+    public string Id => "fill";
+
+    public FillAction(ILogger<FillAction> logger, IDataClient dataClient)
+    {
+        _logger = logger;
+        _dataClient = dataClient;
+    }
+
+    public async Task<UserActionResult> HandleAction(UserActionContext context)
+    {
+        _logger.LogInformation("FillAction triggered, with button id: {buttonId}", context.ButtonId);
+
+        switch (context.ButtonId)
+        {
+            case "add":
+                context.DataMutator.AddFormDataElement(
+                    "Scheme",
+                    new Scheme()
+                    {
+                        TestCustomButtonReadOnlyInput = "Første runde",
+                        TestCustomButtonInput = "Hello a",
+                        description = "Første runde"
+                    }
+                );
+                break;
+            case "update":
+                var originalDataElement = context.DataMutator.FormDataElements.First(de => de.DataType == "Scheme");
+                var originalData = await context.DataMutator.GetFormData(originalDataElement);
+                var data = (Scheme)originalData;
+
+                data.TestCustomButtonReadOnlyInput = "Her kommer det data fra backend";
+                break;
+            case "updateObsolete":
+                var instanceId = context.Instance.Id;
+                var instanceGuid = Guid.Parse(instanceId.Split('/')[1]);
+                var instanceOwner = int.Parse(instanceId.Split('/')[0]);
+                var dataGuid = Guid.Parse(context.Instance.Data.Single().Id);
+
+                var obsoleteData = (Scheme)
+                    await _dataClient.GetFormData(
+                        instanceGuid,
+                        typeof(Scheme),
+                        context.Instance.Org,
+                        context.Instance.AppId.Split('/')[1],
+                        instanceOwner,
+                        dataGuid
+                    );
+                obsoleteData.description = "Obsolete data";
+                var result = UserActionResult.SuccessResult(new List<ClientAction>());
+                result.AddUpdatedDataModel(dataGuid.ToString(), obsoleteData);
+                return result;
+            case "delete":
+                var elementToDelete = context.DataMutator.FormDataElements.First(de => de.DataType == "Scheme");
+                context.DataMutator.RemoveDataElement(elementToDelete);
+                break;
+            case "getClientActions":
+                return UserActionResult.SuccessResult([new ClientAction() { Id = "nextPage" }]);
+
+            case "fail":
+                return UserActionResult.FailureResult(
+                    new ActionError()
+                    {
+                        Code = "machine-readable-error-code",
+                        Message = "Her kommer det en feilmelding",
+                        Metadata = new Dictionary<string, string>() { { "key1", "value1" }, }
+                    },
+                    [new ClientAction() { Id = "nextPage" }],
+                    errorType: ProcessErrorType.Conflict
+                );
+            default:
+                throw new Exception($"Button id {context.ButtonId} not supported");
+        }
+
+        return UserActionResult.SuccessResult(new List<ClientAction>());
+    }
+}
+
 public class LookupAction : IUserAction
 {
     public string Id => "lookup";
diff --git a/test/Altinn.App.Api.Tests/Controllers/DataControllerTests.cs b/test/Altinn.App.Api.Tests/Controllers/DataControllerTests.cs
index ca16fa3f5..c19e18e03 100644
--- a/test/Altinn.App.Api.Tests/Controllers/DataControllerTests.cs
+++ b/test/Altinn.App.Api.Tests/Controllers/DataControllerTests.cs
@@ -30,7 +30,6 @@ public async Task PutDataElement_MissingDataType_ReturnsBadRequest()
         string token = PrincipalUtil.GetOrgToken("nav", "160694123");
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
 
-        TestData.DeleteInstanceAndData(org, app, instanceOwnerPartyId, guid);
         TestData.PrepareInstance(org, app, instanceOwnerPartyId, guid);
 
         using var content = new StringContent("{}", System.Text.Encoding.UTF8, "application/json"); // empty valid json
@@ -53,7 +52,6 @@ public async Task PostBinaryElement_ContentTooLarge_ReturnsBadRequest()
         string token = PrincipalUtil.GetOrgToken("nav", "160694123");
         client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
 
-        TestData.DeleteInstanceAndData(org, app, instanceOwnerPartyId, guid);
         TestData.PrepareInstance(org, app, instanceOwnerPartyId, guid);
 
         using var content = new ByteArrayContent(new byte[1024 * 1024 + 1]); // 1 mb
@@ -93,7 +91,6 @@ public async Task CreateDataElement_BinaryPdf_AnalyserShouldRunOk()
         HttpClient client = GetRootedClient(org, app);
 
         Guid guid = new Guid("0fc98a23-fe31-4ef5-8fb9-dd3f479354cd");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
 
         // Setup the request
@@ -127,7 +124,6 @@ public async Task CreateDataElement_ZeroBytes_BinaryPdf_AnalyserShouldReturnBadR
         HttpClient client = GetRootedClient(org, app);
 
         Guid guid = new Guid("0fc98a23-fe31-4ef5-8fb9-dd3f479354cd");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
 
         // Setup the request
@@ -163,7 +159,6 @@ public async Task CreateDataElement_JpgFakedAsPdf_AnalyserShouldRunAndFail()
         HttpClient client = GetRootedClient(org, app);
 
         Guid guid = new Guid("1fc98a23-fe31-4ef5-8fb9-dd3f479354ce");
-        TestData.DeleteInstanceAndData(org, app, 1337, guid);
         TestData.PrepareInstance(org, app, 1337, guid);
 
         // Setup the request
diff --git a/test/Altinn.App.Api.Tests/Controllers/DataController_LayoutEvaluatorTests.cs b/test/Altinn.App.Api.Tests/Controllers/DataController_LayoutEvaluatorTests.cs
index ef828f916..54239934e 100644
--- a/test/Altinn.App.Api.Tests/Controllers/DataController_LayoutEvaluatorTests.cs
+++ b/test/Altinn.App.Api.Tests/Controllers/DataController_LayoutEvaluatorTests.cs
@@ -74,7 +74,6 @@ public async Task PutDataElement_LegacyLayoutEvaluatorState_ReturnsOk()
         Guid dataGuid = Guid.Parse("f3e04c65-aa70-40ec-84df-087cc2583402");
         HttpClient client = GetRootedClient(org, app, 1337, instanceOwnerPartyId);
 
-        TestData.DeleteInstanceAndData(org, app, instanceOwnerPartyId, instanceGuid);
         TestData.PrepareInstance(org, app, instanceOwnerPartyId, instanceGuid);
 
         // Update data element
diff --git a/test/Altinn.App.Api.Tests/Controllers/DataController_PatchTests.cs b/test/Altinn.App.Api.Tests/Controllers/DataController_PatchTests.cs
index 1426e2f78..1b2c6d88a 100644
--- a/test/Altinn.App.Api.Tests/Controllers/DataController_PatchTests.cs
+++ b/test/Altinn.App.Api.Tests/Controllers/DataController_PatchTests.cs
@@ -66,7 +66,6 @@ public DataControllerPatchTests(WebApplicationFactory<Program> factory, ITestOut
             services.AddSingleton(_dataProcessorMock.Object);
             services.AddSingleton(_formDataValidatorMock.Object);
         };
-        TestData.DeleteInstanceAndData(Org, App, InstanceOwnerPartyId, _instanceGuid);
         TestData.PrepareInstance(Org, App, InstanceOwnerPartyId, _instanceGuid);
     }
 
diff --git a/test/Altinn.App.Api.Tests/Controllers/DataController_PostTests.cs b/test/Altinn.App.Api.Tests/Controllers/DataController_PostTests.cs
index 22de25a8d..c0f1abf72 100644
--- a/test/Altinn.App.Api.Tests/Controllers/DataController_PostTests.cs
+++ b/test/Altinn.App.Api.Tests/Controllers/DataController_PostTests.cs
@@ -33,7 +33,6 @@ public class DataController_PostTests : ApiTestBase, IClassFixture<WebApplicatio
     public DataController_PostTests(WebApplicationFactory<Program> factory, ITestOutputHelper outputHelper)
         : base(factory, outputHelper)
     {
-        TestData.DeleteInstanceAndData(_org, _app, _instanceOwnerPartyId, _instanceGuid);
         TestData.PrepareInstance(_org, _app, _instanceOwnerPartyId, _instanceGuid);
         OverrideServicesForAllTests = (services) =>
         {
diff --git a/test/Altinn.App.Api.Tests/Controllers/ProcessControllerTests.cs b/test/Altinn.App.Api.Tests/Controllers/ProcessControllerTests.cs
index 5a0e5ae51..7c9daba8c 100644
--- a/test/Altinn.App.Api.Tests/Controllers/ProcessControllerTests.cs
+++ b/test/Altinn.App.Api.Tests/Controllers/ProcessControllerTests.cs
@@ -60,7 +60,6 @@ public ProcessControllerTests(WebApplicationFactory<Program> factory, ITestOutpu
             services.AddSingleton(_dataProcessorMock.Object);
             services.AddSingleton(_formDataValidatorMock.Object);
         };
-        TestData.DeleteInstanceAndData(Org, App, InstanceOwnerPartyId, _instanceGuid);
         TestData.PrepareInstance(Org, App, InstanceOwnerPartyId, _instanceGuid);
     }
 
@@ -74,7 +73,6 @@ public async Task Get_ShouldReturnProcessTasks()
 
         HttpClient client = GetRootedClient(org, app, 1337, partyId, 3);
 
-        TestData.DeleteInstanceAndData(org, app, partyId, instanceId);
         TestData.PrepareInstance(org, app, partyId, instanceId);
 
         string url = $"/{org}/{app}/instances/{partyId}/{instanceId}/process";
diff --git a/test/Altinn.App.Api.Tests/Controllers/ValidateController_ValidateInstanceTests.cs b/test/Altinn.App.Api.Tests/Controllers/ValidateController_ValidateInstanceTests.cs
index ff823ca8c..e6a4d9ae6 100644
--- a/test/Altinn.App.Api.Tests/Controllers/ValidateController_ValidateInstanceTests.cs
+++ b/test/Altinn.App.Api.Tests/Controllers/ValidateController_ValidateInstanceTests.cs
@@ -51,7 +51,6 @@ ITestOutputHelper outputHelper
             services.AddSingleton(_dataProcessorMock.Object);
             services.AddSingleton(_formDataValidatorMock.Object);
         };
-        TestData.DeleteInstanceAndData(Org, App, InstanceOwnerPartyId, InstanceGuid);
         TestData.PrepareInstance(Org, App, InstanceOwnerPartyId, InstanceGuid);
     }
 
diff --git a/test/Altinn.App.Api.Tests/CustomWebApplicationFactory.cs b/test/Altinn.App.Api.Tests/CustomWebApplicationFactory.cs
index 8d7b35243..2e5733203 100644
--- a/test/Altinn.App.Api.Tests/CustomWebApplicationFactory.cs
+++ b/test/Altinn.App.Api.Tests/CustomWebApplicationFactory.cs
@@ -215,7 +215,8 @@ private void ConfigureFakeHttpClientHandler(IServiceCollection services)
     }
 
     /// <summary>
-    /// Set this in your test class constructor
+    /// Helper to quickly verify the status code and deserialize the content of a response.
+    /// and print the content to output helper
     /// </summary>
     protected async Task<T> VerifyStatusAndDeserialize<T>(
         HttpResponseMessage response,
@@ -224,7 +225,10 @@ HttpStatusCode expectedStatusCode
     {
         // Deserialize content and log everything if it fails
         var content = await response.Content.ReadAsStringAsync();
-        OutputHelper.WriteLine($"Response content: {content}");
+        OutputHelper.WriteLine(
+            $"{response.RequestMessage?.Method} {response.RequestMessage?.RequestUri?.PathAndQuery}"
+        );
+        OutputHelper.WriteLine(JsonUtils.IndentJson(content));
         // Verify status code
         response.Should().HaveStatusCode(expectedStatusCode);
         try
@@ -239,8 +243,6 @@ HttpStatusCode expectedStatusCode
             OutputHelper.WriteLine(
                 $"Failed to deserialize content of {response.RequestMessage?.Method} request to {response.RequestMessage?.RequestUri} as {ReflectionUtils.GetTypeNameWithGenericArguments<T>()}:"
             );
-
-            OutputHelper.WriteLine(JsonUtils.IndentJson(content));
             OutputHelper.WriteLine(string.Empty);
             throw;
         }
diff --git a/test/Altinn.App.Api.Tests/Data/Instances/tdd/.gitignore b/test/Altinn.App.Api.Tests/Data/Instances/.gitignore
similarity index 64%
rename from test/Altinn.App.Api.Tests/Data/Instances/tdd/.gitignore
rename to test/Altinn.App.Api.Tests/Data/Instances/.gitignore
index 8c777c01b..fa3349399 100644
--- a/test/Altinn.App.Api.Tests/Data/Instances/tdd/.gitignore
+++ b/test/Altinn.App.Api.Tests/Data/Instances/.gitignore
@@ -1,4 +1,4 @@
 # Ignore guid.json files
 ????????-????-????-????-????????????.json
 # ignore copied blobs
-*/*/*/blob/????????-????-????-????-????????????
+**/blob/????????-????-????-????-????????????
diff --git a/test/Altinn.App.Api.Tests/Data/Instances/tdd/task-action/1337/b1135209-628e-4a6e-9efd-e4282068ef41.pretest.json b/test/Altinn.App.Api.Tests/Data/Instances/tdd/task-action/1337/b1135209-628e-4a6e-9efd-e4282068ef41.pretest.json
index 69ac2d877..cb13d3a91 100644
--- a/test/Altinn.App.Api.Tests/Data/Instances/tdd/task-action/1337/b1135209-628e-4a6e-9efd-e4282068ef41.pretest.json
+++ b/test/Altinn.App.Api.Tests/Data/Instances/tdd/task-action/1337/b1135209-628e-4a6e-9efd-e4282068ef41.pretest.json
@@ -26,14 +26,5 @@
     "isSoftDeleted": false,
     "isHardDeleted": false,
     "readStatus": "Read"
-  },
-  "data": [
-    {
-      "id": "de288942-a8af-4f77-a1f1-6e1ede1cd502",
-      "dataType": "default",
-      "contentType": "application/xml",
-      "size": 0,
-      "locked": false
-    }
-  ]
+  }
 }
diff --git a/test/Altinn.App.Api.Tests/Data/TestData.cs b/test/Altinn.App.Api.Tests/Data/TestData.cs
index 88b7d6156..8cdbc3f76 100644
--- a/test/Altinn.App.Api.Tests/Data/TestData.cs
+++ b/test/Altinn.App.Api.Tests/Data/TestData.cs
@@ -96,6 +96,18 @@ Guid dataGuid
         return Path.Combine(dataDirectory, $"{dataGuid}.json");
     }
 
+    public static string GetDataElementBlobContnet(
+        string org,
+        string app,
+        int instanceOwnerId,
+        Guid instanceGuid,
+        Guid dataGuid
+    )
+    {
+        string dataElementPath = GetDataBlobPath(org, app, instanceOwnerId, instanceGuid, dataGuid);
+        return File.ReadAllText(dataElementPath);
+    }
+
     public static string GetDataBlobPath(string org, string app, int instanceOwnerId, Guid instanceGuid, Guid dataGuid)
     {
         string dataDirectory = GetDataDirectory(org, app, instanceOwnerId, instanceGuid);
@@ -142,6 +154,7 @@ public static string GetInstancePath(string org, string app, int instanceOwnerId
 
     public static void PrepareInstance(string org, string app, int instanceOwnerId, Guid instanceGuid)
     {
+        DeleteInstanceAndData(org, app, instanceOwnerId, instanceGuid);
         string instancePath = GetInstancePath(org, app, instanceOwnerId, instanceGuid);
 
         string preInstancePath = instancePath.Replace(".json", ".pretest.json");
@@ -185,7 +198,7 @@ public static void DeleteInstanceAndData(string org, string app, int instanceOwn
         }
     }
 
-    public static void DeleteDataForInstance(string org, string app, int instanceOwnerId, Guid instanceGuid)
+    private static void DeleteDataForInstance(string org, string app, int instanceOwnerId, Guid instanceGuid)
     {
         string path = GetDataDirectory(org, app, instanceOwnerId, instanceGuid);
 
diff --git a/test/Altinn.App.Api.Tests/Data/apps/tdd/task-action/config/applicationmetadata.json b/test/Altinn.App.Api.Tests/Data/apps/tdd/task-action/config/applicationmetadata.json
index 04fdae29e..f5a79437f 100644
--- a/test/Altinn.App.Api.Tests/Data/apps/tdd/task-action/config/applicationmetadata.json
+++ b/test/Altinn.App.Api.Tests/Data/apps/tdd/task-action/config/applicationmetadata.json
@@ -1,6 +1,6 @@
 {
-  "id": "ttd/task-action",
-  "org": "ttd",
+  "id": "tdd/task-action",
+  "org": "tdd",
   "title": {
     "nb": "task-action"
   },
@@ -25,7 +25,7 @@
       ],
       "appLogic": {
         "autoCreate": true,
-        "classRef": "Altinn.App.Models.Scheme",
+        "classRef": "Altinn.App.Api.Tests.Data.apps.tdd.task_action.config.models.Scheme",
         "allowAnonymousOnStateless": false,
         "autoDeleteOnProcessEnd": false
       },
@@ -50,4 +50,4 @@
   "createdBy": "tjololo",
   "lastChanged": "2023-05-31T08:03:25.9385925Z",
   "lastChangedBy": "tjololo"
-}
\ No newline at end of file
+}
diff --git a/test/Altinn.App.Api.Tests/Data/apps/tdd/task-action/config/models/Scheme.cs b/test/Altinn.App.Api.Tests/Data/apps/tdd/task-action/config/models/Scheme.cs
new file mode 100644
index 000000000..84adfbabd
--- /dev/null
+++ b/test/Altinn.App.Api.Tests/Data/apps/tdd/task-action/config/models/Scheme.cs
@@ -0,0 +1,18 @@
+#pragma warning disable IDE1006 // Naming Styles
+namespace Altinn.App.Api.Tests.Data.apps.tdd.task_action.config.models;
+
+/// <summary>
+/// Class for the model
+/// </summary>
+public class Scheme
+{
+    public string? name { get; set; }
+
+    public string? description { get; set; }
+
+    public string? TestCustomButtonInput { get; set; }
+
+    public string? TestCustomButtonReadOnlyInput { get; set; }
+}
+
+#pragma warning restore IDE1006 // Naming Styles