diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringSearchResults.cs b/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringSearchResults.cs
index 3919bb96..bed2d35e 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringSearchResults.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringSearchResults.cs
@@ -1,4 +1,6 @@
-using System.Text.Json.Serialization;
+#nullable enable
+
+using System.Text.Json.Serialization;
 
 namespace SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.Api;
 
@@ -8,5 +10,5 @@ public class RtqMonitoringSearchResults
     public long TotalCount { get; set; }
 
     [JsonPropertyName("taskMetas")]
-    public RtqMonitoringTaskMeta[] TaskMetas { get; set; }
+    public RtqMonitoringTaskMeta[] TaskMetas { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskMeta.cs b/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskMeta.cs
index 48e3ebed..6135c4bb 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskMeta.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskMeta.cs
@@ -1,4 +1,6 @@
-using System.Text.Json.Serialization;
+#nullable enable
+
+using System.Text.Json.Serialization;
 
 using SkbKontur.Cassandra.DistributedTaskQueue.Cassandra.Entities;
 using SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.Json;
@@ -8,10 +10,10 @@ namespace SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.Api;
 public class RtqMonitoringTaskMeta
 {
     [JsonPropertyName("name")]
-    public string Name { get; set; }
+    public string Name { get; set; } = null!;
 
     [JsonPropertyName("id")]
-    public string Id { get; set; }
+    public string Id { get; set; } = null!;
 
     [JsonPropertyName("ticks")]
     [JsonConverter(typeof(LongToStringConverter))]
@@ -50,7 +52,7 @@ public class RtqMonitoringTaskMeta
     public TaskState State { get; set; }
 
     [JsonPropertyName("taskActions")]
-    public TaskActions TaskActions { get; set; }
+    public TaskActions? TaskActions { get; set; }
 
     [JsonPropertyName("attempts")]
     public int Attempts { get; set; }
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskModel.cs b/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskModel.cs
index 7819f26f..af66d92f 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskModel.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Api/RtqMonitoringTaskModel.cs
@@ -1,4 +1,6 @@
-using System.Text.Json.Serialization;
+#nullable enable
+
+using System.Text.Json.Serialization;
 
 using SkbKontur.Cassandra.DistributedTaskQueue.Handling;
 using SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.Json;
@@ -10,15 +12,15 @@ public class RtqMonitoringTaskModel
     public static RtqMonitoringTaskModel Empty => new();
 
     [JsonPropertyName("taskMeta")]
-    public RtqMonitoringTaskMeta TaskMeta { get; set; }
+    public RtqMonitoringTaskMeta TaskMeta { get; set; } = null!;
 
     [JsonPropertyName("taskData")]
     [JsonConverter(typeof(TaskDataJsonSerializer))]
-    public IRtqTaskData TaskData { get; set; }
+    public IRtqTaskData TaskData { get; set; } = null!;
 
     [JsonPropertyName("childTaskIds")]
-    public string[] ChildTaskIds { get; set; }
+    public string[] ChildTaskIds { get; set; } = null!;
 
     [JsonPropertyName("exceptionInfos")]
-    public string[] ExceptionInfos { get; set; }
+    public string[] ExceptionInfos { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Api/TimestampRange.cs b/Cassandra.DistributedTaskQueue.Monitoring/Api/TimestampRange.cs
index c02735f0..cbde3b87 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Api/TimestampRange.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Api/TimestampRange.cs
@@ -1,4 +1,6 @@
-using System.Text.Json.Serialization;
+#nullable enable
+
+using System.Text.Json.Serialization;
 
 using SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.Json;
 using SkbKontur.Cassandra.TimeBasedUuid;
@@ -9,9 +11,9 @@ public class TimestampRange
 {
     [JsonPropertyName("lowerBound")]
     [JsonConverter(typeof(TimestampJsonConverter))]
-    public Timestamp LowerBound { get; set; }
+    public Timestamp LowerBound { get; set; } = null!;
 
     [JsonPropertyName("upperBound")]
     [JsonConverter(typeof(TimestampJsonConverter))]
-    public Timestamp UpperBound { get; set; }
+    public Timestamp UpperBound { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/ElasticsearchResponseWrapperExtensions.cs b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/ElasticsearchResponseWrapperExtensions.cs
index c0508a4d..71322bc8 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/ElasticsearchResponseWrapperExtensions.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/ElasticsearchResponseWrapperExtensions.cs
@@ -1,4 +1,6 @@
-using System;
+#nullable enable
+
+using System;
 using System.Linq;
 using System.Text;
 using System.Text.Json;
@@ -26,7 +28,7 @@ public static void DieIfBulkRequestFailed(this StringResponse response)
     {
         response.EnsureSuccess();
         var bulkResponse = JsonSerializer.Deserialize<BulkResponse>(response.Body);
-        if (bulkResponse.HasErrors)
+        if (bulkResponse!.HasErrors)
         {
             var innerExceptions = bulkResponse
                                   .Items
@@ -39,7 +41,7 @@ public static void DieIfBulkRequestFailed(this StringResponse response)
         }
     }
 
-    private static string ExtendErrorMessageWithElasticInfo<T>(this T response, string errorMessage)
+    private static string ExtendErrorMessageWithElasticInfo<T>(this T? response, string errorMessage)
         where T : IElasticsearchResponse
     {
         var fullErrorMessage = new StringBuilder($"ElasticSearch error: '{errorMessage}'").AppendLine();
@@ -58,7 +60,7 @@ private static string ExtendErrorMessageWithElasticInfo<T>(this T response, stri
         return fullErrorMessage.ToString();
     }
 
-    private static Exception CreateExceptionIfError(ResponseBase responseItem, int requestNumber)
+    private static Exception? CreateExceptionIfError(ResponseBase responseItem, int requestNumber)
     {
         return responseItem.Status >= 400 && responseItem.Status < 600
                    ? new InvalidOperationException($"Request number #{requestNumber} failed: '{responseItem.ToPrettyJson()}'")
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitInfo.cs b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitInfo.cs
index cdc7f48c..75fe33b6 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitInfo.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitInfo.cs
@@ -1,9 +1,11 @@
-using System.Text.Json.Serialization;
+#nullable enable
+
+using System.Text.Json.Serialization;
 
 namespace SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.ElasticsearchClientExtensions.Responses.Search;
 
 internal class HitInfo
 {
     [JsonPropertyName("_id")]
-    public string Id { get; set; }
+    public string Id { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitsCollection.cs b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitsCollection.cs
index 9743abf2..70330525 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitsCollection.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/HitsCollection.cs
@@ -1,4 +1,6 @@
-using System.Text.Json.Serialization;
+#nullable enable
+
+using System.Text.Json.Serialization;
 
 using SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.Json;
 
@@ -11,5 +13,5 @@ internal class HitsCollection
     public long TotalCount { get; set; }
 
     [JsonPropertyName("hits")]
-    public HitInfo[] Hits { get; set; }
+    public HitInfo[] Hits { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/SearchResponse.cs b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/SearchResponse.cs
index c2f36e5b..48dbdbbf 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/SearchResponse.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/ElasticsearchClientExtensions/Responses/Search/SearchResponse.cs
@@ -1,9 +1,11 @@
-using System.Text.Json.Serialization;
+#nullable enable
+
+using System.Text.Json.Serialization;
 
 namespace SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.ElasticsearchClientExtensions.Responses.Search;
 
 internal class SearchResponse
 {
     [JsonPropertyName("hits")]
-    public HitsCollection Hits { get; set; }
+    public HitsCollection Hits { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Indexer/RtqElasticsearchIndexerSettings.cs b/Cassandra.DistributedTaskQueue.Monitoring/Indexer/RtqElasticsearchIndexerSettings.cs
index bfe82107..6cef3801 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Indexer/RtqElasticsearchIndexerSettings.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Indexer/RtqElasticsearchIndexerSettings.cs
@@ -1,4 +1,6 @@
-using System;
+#nullable enable
+
+using System;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Indexer/TaskMetaProcessor.cs b/Cassandra.DistributedTaskQueue.Monitoring/Indexer/TaskMetaProcessor.cs
index bbb61f76..52ceb0d7 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Indexer/TaskMetaProcessor.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Indexer/TaskMetaProcessor.cs
@@ -1,4 +1,6 @@
-using System;
+#nullable enable
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text.Json;
@@ -67,22 +69,22 @@ private void IndexMetas(TaskMetaInformation[] batch)
     {
         var taskDatas = perfGraphiteReporter.ReportTiming("ReadTaskDatas", () => taskDataStorage.Read(batch));
         var taskExceptionInfos = perfGraphiteReporter.ReportTiming("ReadTaskExceptionInfos", () => taskExceptionInfoStorage.Read(batch));
-        var enrichedBatch = new ( /*[NotNull]*/ TaskMetaInformation TaskMeta, /*[NotNull, ItemNotNull]*/ TaskExceptionInfo[] TaskExceptionInfos, /*[CanBeNull]*/ object TaskData)[batch.Length];
+        var enrichedBatch = new ( TaskMetaInformation TaskMeta, TaskExceptionInfo[] TaskExceptionInfos, object? TaskData)[batch.Length];
         for (var i = 0; i < batch.Length; i++)
         {
             var taskMeta = batch[i];
-            object taskDataObj = null;
+            object? taskDataObj = null;
             if (taskDatas.TryGetValue(taskMeta.Id, out var taskData))
             {
                 if (taskDataRegistry.TryGetTaskType(taskMeta.Name, out var taskType))
-                    taskDataObj = TryDeserializeTaskData(taskType, taskData, taskMeta);
+                    taskDataObj = TryDeserializeTaskData(taskType!, taskData, taskMeta);
             }
             enrichedBatch[i] = (taskMeta, taskExceptionInfos[taskMeta.Id], taskDataObj);
         }
         perfGraphiteReporter.ReportTiming("IndexBatch", () => IndexBatch(enrichedBatch));
     }
 
-    private void IndexBatch((TaskMetaInformation TaskMeta, TaskExceptionInfo[] TaskExceptionInfos, object TaskData)[] batch)
+    private void IndexBatch((TaskMetaInformation TaskMeta, TaskExceptionInfo[] TaskExceptionInfos, object? TaskData)[] batch)
     {
         logger.Info("IndexBatch: {BatchLength} tasks", new {BatchLength = batch.Length});
         var payload = new string[batch.Length * 2];
@@ -127,7 +129,7 @@ private object TryDeserializeTaskData(Type taskType, byte[] taskData, TaskMetaIn
         }
     }
 
-    private static object BuildTaskIndexedInfo(TaskMetaInformation taskMeta, TaskExceptionInfo[] taskExceptionInfos, object taskData)
+    private static object BuildTaskIndexedInfo(TaskMetaInformation taskMeta, TaskExceptionInfo[] taskExceptionInfos, object? taskData)
     {
         var executionDurationTicks = taskMeta.ExecutionDurationTicks;
         var meta = new MetaIndexedInfo
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Json/JsonObjectExtensions.cs b/Cassandra.DistributedTaskQueue.Monitoring/Json/JsonObjectExtensions.cs
index 6520f77b..114bcc11 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Json/JsonObjectExtensions.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Json/JsonObjectExtensions.cs
@@ -1,4 +1,6 @@
-using System.Text.Json;
+#nullable enable
+
+using System.Text.Json;
 using System.Text.Json.Serialization;
 
 namespace SkbKontur.Cassandra.DistributedTaskQueue.Monitoring.Json;
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/RtqElasticsearchOffsetStorage.cs b/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/RtqElasticsearchOffsetStorage.cs
index b1187265..bb06ad67 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/RtqElasticsearchOffsetStorage.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/RtqElasticsearchOffsetStorage.cs
@@ -1,4 +1,6 @@
-using System;
+#nullable enable
+
+using System;
 using System.Text.Json;
 
 using Elasticsearch.Net;
@@ -28,7 +30,7 @@ public string GetDescription()
         return $"RtqElasticsearchOffsetStorage with IndexName: {elasticIndexName}, BladeKey: {bladeKey}";
     }
 
-    public void Write(string newOffset)
+    public void Write(string? newOffset)
     {
         var payload = new OffsetStorageElement {Offset = newOffset};
         var postData = PostData.String(JsonSerializer.Serialize(payload));
@@ -41,7 +43,7 @@ public void Write(string newOffset)
 #pragma warning restore CS0618
     }
 
-    public string Read()
+    public string? Read()
     {
         var stringResponse = elasticsearchClient.UseElastic7
                                  ? elasticsearchClient.Get<StringResponse>(elasticIndexName, bladeKey, allowNotFoundStatusCode).EnsureSuccess()
@@ -55,7 +57,7 @@ public string Read()
         if (elasticResponse?.Source == null || !elasticResponse.Found)
             return GetDefaultOffset();
 
-        return elasticResponse.Source.Offset;
+        return elasticResponse.Source?.Offset;
     }
 
     private string GetDefaultOffset()
@@ -78,6 +80,6 @@ private string GetDefaultOffset()
 
     private class OffsetStorageElement
     {
-        public string Offset { get; set; }
+        public string? Offset { get; set; }
     }
 }
\ No newline at end of file
diff --git a/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/TaskIndexedInfo.cs b/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/TaskIndexedInfo.cs
index f204ab9b..6949d985 100644
--- a/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/TaskIndexedInfo.cs
+++ b/Cassandra.DistributedTaskQueue.Monitoring/Storage/Writing/TaskIndexedInfo.cs
@@ -1,6 +1,6 @@
-using System.Collections.Generic;
+#nullable enable
 
-using JetBrains.Annotations;
+using System.Collections.Generic;
 
 using System.Text.Json.Serialization;
 
@@ -12,7 +12,7 @@ public TaskIndexedInfo()
     {
     }
 
-    public TaskIndexedInfo([NotNull] MetaIndexedInfo meta, [NotNull] string exceptionInfo, [CanBeNull] object data)
+    public TaskIndexedInfo(MetaIndexedInfo meta, string exceptionInfo, object? data)
     {
         Meta = meta;
         ExceptionInfo = exceptionInfo;
@@ -20,12 +20,12 @@ public TaskIndexedInfo([NotNull] MetaIndexedInfo meta, [NotNull] string exceptio
             Data = new Dictionary<string, object> {{meta.Name, data}};
     }
 
-    public MetaIndexedInfo Meta { get; set; }
+    public MetaIndexedInfo Meta { get; set; } = null!;
 
     [JsonConverter(typeof(TruncateLongStringsConverter2K))]
-    public string ExceptionInfo { get; set; }
+    public string ExceptionInfo { get; set; } = null!;
 
     // NOTE! Using TaskTypeName->TaskData dictionary here to avoid type conflicts between fields with the same name in different TaskData contracts
     // since we must index all TaskData types into single elasticsearch mapping type (see https://www.elastic.co/guide/en/elasticsearch/reference/current/removal-of-types.html)
-    public Dictionary<string, object> Data { get; set; }
+    public Dictionary<string, object> Data { get; set; } = null!;
 }
\ No newline at end of file