diff --git a/src/main/kotlin/ru/kotlin/homework/network/NetworkLogger.kt b/src/main/kotlin/ru/kotlin/homework/network/NetworkLogger.kt
index a5f33c5..0117efb 100644
--- a/src/main/kotlin/ru/kotlin/homework/network/NetworkLogger.kt
+++ b/src/main/kotlin/ru/kotlin/homework/network/NetworkLogger.kt
@@ -10,14 +10,22 @@ import java.time.LocalDateTime
  * Известный вам список ошибок
  */
 sealed class ApiException(message: String) : Throwable(message) {
-    data object NotAuthorized : ApiException("Not authorized")
-    data object NetworkException : ApiException("Not connected")
-    data object UnknownException: ApiException("Unknown exception")
+    data object NotAuthorized : ApiException("Not authorized") {
+        private fun readResolve(): Any = NotAuthorized
+    }
+
+    data object NetworkException : ApiException("Not connected") {
+        private fun readResolve(): Any = NetworkException
+    }
+
+    data object UnknownException: ApiException("Unknown exception") {
+        private fun readResolve(): Any = UnknownException
+    }
 }
 
 class ErrorLogger<E : Throwable> {
 
-    val errors = mutableListOf<Pair<LocalDateTime, E>>()
+    private val errors = mutableListOf<Pair<LocalDateTime, E>>()
 
     fun log(response: NetworkResponse<*, E>) {
         if (response is Failure) {
@@ -42,7 +50,10 @@ fun processThrowables(logger: ErrorLogger<Throwable>) {
     logger.dumpLog()
 }
 
-fun processApiErrors(apiExceptionLogger: ErrorLogger<ApiException>) {
+// Type mismatch: inferred type is ErrorLogger<Throwable> but ErrorLogger<ApiException> was expected
+//   fix: logger экземпляр ErrorLogger<Throwable>, и на входе ожидается Throwable вместо ApiException
+//        ApiException наследник Throwable, разрешение принимать в том числе и наследников дает модификатор "IN"
+fun processApiErrors(apiExceptionLogger: ErrorLogger<in ApiException>) {
     apiExceptionLogger.log(Success("Success"))
     Thread.sleep(100)
     apiExceptionLogger.log(Success(Circle))
diff --git a/src/main/kotlin/ru/kotlin/homework/network/NetworkResponse.kt b/src/main/kotlin/ru/kotlin/homework/network/NetworkResponse.kt
index 3018c40..58c5745 100644
--- a/src/main/kotlin/ru/kotlin/homework/network/NetworkResponse.kt
+++ b/src/main/kotlin/ru/kotlin/homework/network/NetworkResponse.kt
@@ -9,19 +9,27 @@ import java.time.LocalDateTime
 /**
  * Network result
  */
-sealed class NetworkResponse<T, R> {
+// Type parameter T is declared as 'out' but occurs in 'invariant' position in type NetworkResponse<T, Nothing>
+//   fix: родитель должен иметь такой же модификатор OUT как и дочка
+// Type mismatch: inferred type is Success<String> but NetworkResponse<String, kotlin.Error /* = java.lang.Error */> was expected
+//   fix: второй параметр так же "OUT" для обобщенного типа как ковариантного
+sealed class NetworkResponse<out T, out R> {
     val responseDateTime: LocalDateTime = LocalDateTime.now()
 }
 
 /**
  * Network success
  */
-data class Success<T, R>(val resp: T): NetworkResponse<T, R>()
+// Success - наследник без R, заменяем R на Nothing
+// Type mismatch: inferred type is Success<String> but NetworkResponse<Any, kotlin.Error /* = java.lang.Error */> was expected
+//   fix: Any - предок для String, используем "OUT" для обобщенного типа как ковариантного
+data class Success<out T>(val resp: T): NetworkResponse<T, Nothing>()
 
 /**
  * Network error
  */
-data class Failure<T, R>(val error: R): NetworkResponse<T, R>()
+// Failure - наследник без T, заменяем T на Nothing
+data class Failure<R>(val error: R): NetworkResponse<Nothing, R>()
 
 val s1 = Success("Message")
 val r11: NetworkResponse<String, Error> = s1
@@ -42,4 +50,4 @@ val er4: NetworkResponse<Any, Throwable> = e
 
 val er5: NetworkResponse<Int, Throwable> = Failure(IllegalArgumentException("message"))
 
-val message = e.error.message
\ No newline at end of file
+val message = e.error.message