diff --git a/ktor-client/ktor-client-cio/jvmAndPosix/src/io/ktor/client/engine/cio/utils.kt b/ktor-client/ktor-client-cio/jvmAndPosix/src/io/ktor/client/engine/cio/utils.kt
index 325ca90bd92..b2b92c93706 100644
--- a/ktor-client/ktor-client-cio/jvmAndPosix/src/io/ktor/client/engine/cio/utils.kt
+++ b/ktor-client/ktor-client-cio/jvmAndPosix/src/io/ktor/client/engine/cio/utils.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client.engine.cio
 
@@ -14,8 +14,6 @@ import io.ktor.http.content.*
 import io.ktor.util.date.*
 import io.ktor.utils.io.*
 import io.ktor.utils.io.CancellationException
-import io.ktor.utils.io.core.*
-import io.ktor.utils.io.errors.*
 import io.ktor.websocket.*
 import kotlinx.coroutines.*
 import kotlinx.io.IOException
diff --git a/ktor-client/ktor-client-cio/jvmAndPosix/test/CIOEngineTest.kt b/ktor-client/ktor-client-cio/jvmAndPosix/test/CIOEngineTest.kt
index f442d2f88df..8844cac9533 100644
--- a/ktor-client/ktor-client-cio/jvmAndPosix/test/CIOEngineTest.kt
+++ b/ktor-client/ktor-client-cio/jvmAndPosix/test/CIOEngineTest.kt
@@ -1,8 +1,10 @@
 /*
- * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
+
+package io.ktor.client.engine.cio
+
 import io.ktor.client.*
-import io.ktor.client.engine.cio.*
 import io.ktor.client.plugins.sse.*
 import io.ktor.client.plugins.websocket.*
 import io.ktor.client.request.*
@@ -11,7 +13,6 @@ import io.ktor.http.*
 import io.ktor.network.selector.*
 import io.ktor.network.sockets.*
 import io.ktor.utils.io.*
-import io.ktor.utils.io.core.*
 import io.ktor.websocket.*
 import kotlinx.coroutines.*
 import kotlinx.coroutines.flow.*
diff --git a/ktor-client/ktor-client-cio/jvmAndPosix/test/ConnectionFactoryTest.kt b/ktor-client/ktor-client-cio/jvmAndPosix/test/ConnectionFactoryTest.kt
index a4354f66eda..8c82620013f 100644
--- a/ktor-client/ktor-client-cio/jvmAndPosix/test/ConnectionFactoryTest.kt
+++ b/ktor-client/ktor-client-cio/jvmAndPosix/test/ConnectionFactoryTest.kt
@@ -1,10 +1,11 @@
 /*
- * Copyright 2014-2023 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
-import io.ktor.client.engine.cio.*
+
+package io.ktor.client.engine.cio
+
 import io.ktor.network.selector.*
 import io.ktor.network.sockets.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlin.test.*
 
diff --git a/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt b/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt
index 874ff130392..75aabe09998 100644
--- a/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt
+++ b/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client
 
@@ -1449,7 +1449,7 @@ public class HttpClient(
             @Suppress("UNCHECKED_CAST")
             val plugin = installedFeatures[key as AttributeKey<Any>]
 
-            if (plugin is Closeable) {
+            if (plugin is AutoCloseable) {
                 plugin.close()
             }
         }
diff --git a/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt b/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt
index 7bfadfaa3fd..14ca79b3887 100644
--- a/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt
+++ b/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt
@@ -1,11 +1,10 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client.engine
 
 import io.ktor.util.*
-import io.ktor.utils.io.core.*
 import kotlinx.atomicfu.*
 import kotlinx.coroutines.*
 import kotlin.coroutines.*
@@ -58,19 +57,4 @@ public abstract class HttpClientEngineBase(private val engineName: String) : Htt
 public class ClientEngineClosedException(override val cause: Throwable? = null) :
     IllegalStateException("Client already closed")
 
-/**
- * Closes [CoroutineDispatcher] if it's [CloseableCoroutineDispatcher] or [Closeable].
- */
-@OptIn(ExperimentalCoroutinesApi::class)
-private fun CoroutineDispatcher.close() {
-    try {
-        when (this) {
-            is CloseableCoroutineDispatcher -> close()
-            is Closeable -> close()
-        }
-    } catch (ignore: Throwable) {
-        // Some closeable dispatchers like Dispatchers.IO can't be closed.
-    }
-}
-
 internal expect fun ioDispatcher(): CoroutineDispatcher
diff --git a/ktor-client/ktor-client-core/jvm/src/io/ktor/client/plugins/cache/storage/FileCacheStorage.kt b/ktor-client/ktor-client-core/jvm/src/io/ktor/client/plugins/cache/storage/FileCacheStorage.kt
index 02a90a6de93..b9b0660481d 100644
--- a/ktor-client/ktor-client-core/jvm/src/io/ktor/client/plugins/cache/storage/FileCacheStorage.kt
+++ b/ktor-client/ktor-client-core/jvm/src/io/ktor/client/plugins/cache/storage/FileCacheStorage.kt
@@ -10,7 +10,6 @@ import io.ktor.util.*
 import io.ktor.util.collections.*
 import io.ktor.util.date.*
 import io.ktor.utils.io.*
-import io.ktor.utils.io.core.*
 import io.ktor.utils.io.jvm.javaio.*
 import kotlinx.coroutines.*
 import kotlinx.coroutines.sync.*
diff --git a/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlNativeTests.kt b/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlNativeTests.kt
index 6204db99a37..366ca4da5a7 100644
--- a/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlNativeTests.kt
+++ b/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlNativeTests.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client.engine.curl.test
 
@@ -9,9 +9,7 @@ import io.ktor.client.call.*
 import io.ktor.client.engine.curl.*
 import io.ktor.client.request.*
 import io.ktor.client.statement.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
-import kotlin.native.concurrent.*
 import kotlin.test.*
 
 class CurlNativeTests {
diff --git a/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlProxyTest.kt b/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlProxyTest.kt
index 73b64693d69..e0d8e2b350e 100644
--- a/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlProxyTest.kt
+++ b/ktor-client/ktor-client-curl/desktop/test/io/ktor/client/engine/curl/test/CurlProxyTest.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client.engine.curl.test
 
@@ -11,7 +11,6 @@ import io.ktor.client.engine.curl.*
 import io.ktor.client.request.*
 import io.ktor.client.statement.*
 import io.ktor.http.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlin.test.*
 
diff --git a/ktor-client/ktor-client-tests/common/src/io/ktor/client/tests/utils/CommonClientTestUtils.kt b/ktor-client/ktor-client-tests/common/src/io/ktor/client/tests/utils/CommonClientTestUtils.kt
index f507e9d3114..444edf36ed3 100644
--- a/ktor-client/ktor-client-tests/common/src/io/ktor/client/tests/utils/CommonClientTestUtils.kt
+++ b/ktor-client/ktor-client-tests/common/src/io/ktor/client/tests/utils/CommonClientTestUtils.kt
@@ -7,7 +7,6 @@ package io.ktor.client.tests.utils
 import io.ktor.client.*
 import io.ktor.client.engine.*
 import io.ktor.test.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlin.time.Duration
 import kotlin.time.Duration.Companion.minutes
diff --git a/ktor-client/ktor-client-winhttp/windows/src/io/ktor/client/engine/winhttp/internal/WinHttpResponseData.kt b/ktor-client/ktor-client-winhttp/windows/src/io/ktor/client/engine/winhttp/internal/WinHttpResponseData.kt
index 0271f8fb464..93df7931549 100644
--- a/ktor-client/ktor-client-winhttp/windows/src/io/ktor/client/engine/winhttp/internal/WinHttpResponseData.kt
+++ b/ktor-client/ktor-client-winhttp/windows/src/io/ktor/client/engine/winhttp/internal/WinHttpResponseData.kt
@@ -1,16 +1,14 @@
 /*
- * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.client.engine.winhttp.internal
 
-import io.ktor.client.plugins.sse.*
 import io.ktor.client.request.*
 import io.ktor.http.*
 import io.ktor.http.cio.*
 import io.ktor.util.date.*
 import io.ktor.utils.io.*
-import io.ktor.utils.io.core.*
 import kotlin.coroutines.*
 
 internal class WinHttpResponseData(
diff --git a/ktor-client/ktor-client-winhttp/windows/test/io/ktor/client/engine/winhttp/WinHttpProxyTest.kt b/ktor-client/ktor-client-winhttp/windows/test/io/ktor/client/engine/winhttp/WinHttpProxyTest.kt
index bd977ceb70c..a14241ae849 100644
--- a/ktor-client/ktor-client-winhttp/windows/test/io/ktor/client/engine/winhttp/WinHttpProxyTest.kt
+++ b/ktor-client/ktor-client-winhttp/windows/test/io/ktor/client/engine/winhttp/WinHttpProxyTest.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client.engine.winhttp
 
@@ -8,7 +8,6 @@ import io.ktor.client.*
 import io.ktor.client.call.*
 import io.ktor.client.engine.*
 import io.ktor.client.request.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlin.test.*
 
diff --git a/ktor-io/api/ktor-io.klib.api b/ktor-io/api/ktor-io.klib.api
index 55c7cd72c86..e691706152e 100644
--- a/ktor-io/api/ktor-io.klib.api
+++ b/ktor-io/api/ktor-io.klib.api
@@ -53,7 +53,7 @@ abstract interface <#A: kotlin/Any> io.ktor.utils.io.pool/ObjectPool : kotlin/Au
     open fun close() // io.ktor.utils.io.pool/ObjectPool.close|close(){}[0]
 }
 
-abstract interface io.ktor.utils.io.core/Closeable { // io.ktor.utils.io.core/Closeable|null[0]
+abstract interface io.ktor.utils.io.core/Closeable : kotlin/AutoCloseable { // io.ktor.utils.io.core/Closeable|null[0]
     abstract fun close() // io.ktor.utils.io.core/Closeable.close|close(){}[0]
 }
 
diff --git a/ktor-io/common/src/io/ktor/utils/io/core/Closeable.kt b/ktor-io/common/src/io/ktor/utils/io/core/Closeable.kt
index 90567a0231f..043fab49be2 100644
--- a/ktor-io/common/src/io/ktor/utils/io/core/Closeable.kt
+++ b/ktor-io/common/src/io/ktor/utils/io/core/Closeable.kt
@@ -4,25 +4,9 @@
 
 package io.ktor.utils.io.core
 
-public expect interface Closeable {
-    public fun close()
-}
+import kotlin.use as stdlibUse
 
-public inline fun <T : Closeable?, R> T.use(block: (T) -> R): R {
-    var closed = false
-    try {
-        return block(this)
-    } catch (cause: Throwable) {
-        closed = true
-        try {
-            this?.close()
-        } catch (closeException: Throwable) {
-            cause.addSuppressed(closeException)
-        }
-        throw cause
-    } finally {
-        if (!closed) {
-            this?.close()
-        }
-    }
-}
+public expect interface Closeable : AutoCloseable
+
+@Deprecated("Use stdlib implementation instead. Remove import of this function", ReplaceWith("stdlibUse(block)"))
+public inline fun <T : Closeable?, R> T.use(block: (T) -> R): R = stdlibUse(block)
diff --git a/ktor-io/js/src/io/ktor/utils/io/core/Closeable.js.kt b/ktor-io/js/src/io/ktor/utils/io/core/Closeable.js.kt
index 09561abbac7..63ae1eeb0f4 100644
--- a/ktor-io/js/src/io/ktor/utils/io/core/Closeable.js.kt
+++ b/ktor-io/js/src/io/ktor/utils/io/core/Closeable.js.kt
@@ -4,6 +4,6 @@
 
 package io.ktor.utils.io.core
 
-public actual interface Closeable {
-    public actual fun close()
+public actual interface Closeable : AutoCloseable {
+    override fun close()
 }
diff --git a/ktor-io/posix/src/io/ktor/utils/io/core/Closeable.posix.kt b/ktor-io/posix/src/io/ktor/utils/io/core/Closeable.posix.kt
index 09561abbac7..63ae1eeb0f4 100644
--- a/ktor-io/posix/src/io/ktor/utils/io/core/Closeable.posix.kt
+++ b/ktor-io/posix/src/io/ktor/utils/io/core/Closeable.posix.kt
@@ -4,6 +4,6 @@
 
 package io.ktor.utils.io.core
 
-public actual interface Closeable {
-    public actual fun close()
+public actual interface Closeable : AutoCloseable {
+    override fun close()
 }
diff --git a/ktor-io/wasmJs/src/io/ktor/utils/io/core/Closeable.wasmJs.kt b/ktor-io/wasmJs/src/io/ktor/utils/io/core/Closeable.wasmJs.kt
index 09561abbac7..63ae1eeb0f4 100644
--- a/ktor-io/wasmJs/src/io/ktor/utils/io/core/Closeable.wasmJs.kt
+++ b/ktor-io/wasmJs/src/io/ktor/utils/io/core/Closeable.wasmJs.kt
@@ -4,6 +4,6 @@
 
 package io.ktor.utils.io.core
 
-public actual interface Closeable {
-    public actual fun close()
+public actual interface Closeable : AutoCloseable {
+    override fun close()
 }
diff --git a/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TCPSocketTest.kt b/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TCPSocketTest.kt
index bece892c452..71f9543899b 100644
--- a/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TCPSocketTest.kt
+++ b/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TCPSocketTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.network.sockets.tests
@@ -7,7 +7,6 @@ package io.ktor.network.sockets.tests
 import io.ktor.network.sockets.*
 import io.ktor.utils.io.*
 import io.ktor.utils.io.CancellationException
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlinx.io.*
 import kotlin.test.*
diff --git a/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TestUtils.kt b/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TestUtils.kt
index 3e7f36121bb..1a255234492 100644
--- a/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TestUtils.kt
+++ b/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/TestUtils.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.network.sockets.tests
@@ -7,7 +7,6 @@ package io.ktor.network.sockets.tests
 import io.ktor.network.selector.*
 import io.ktor.test.dispatcher.*
 import io.ktor.util.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlin.time.*
 import kotlin.time.Duration.Companion.seconds
diff --git a/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/UDPSocketTest.kt b/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/UDPSocketTest.kt
index 5c9d784b5d7..1c947038cb6 100644
--- a/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/UDPSocketTest.kt
+++ b/ktor-network/jvmAndPosix/test/io/ktor/network/sockets/tests/UDPSocketTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.network.sockets.tests
@@ -11,6 +11,7 @@ import kotlinx.coroutines.*
 import kotlinx.io.*
 import kotlin.random.*
 import kotlin.test.*
+import kotlin.use
 
 class UDPSocketTest {
 
diff --git a/ktor-network/ktor-network-tls/jvm/src/io/ktor/network/tls/TLSClientHandshake.kt b/ktor-network/ktor-network-tls/jvm/src/io/ktor/network/tls/TLSClientHandshake.kt
index ce5a63d79c7..be2fe7b3e91 100644
--- a/ktor-network/ktor-network-tls/jvm/src/io/ktor/network/tls/TLSClientHandshake.kt
+++ b/ktor-network/ktor-network-tls/jvm/src/io/ktor/network/tls/TLSClientHandshake.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.network.tls
 
@@ -21,6 +21,7 @@ import javax.crypto.*
 import javax.crypto.spec.*
 import javax.security.auth.x500.*
 import kotlin.coroutines.*
+import kotlin.use
 
 internal class TLSClientHandshake(
     rawInput: ByteReadChannel,
diff --git a/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/Certificates.kt b/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/Certificates.kt
index 5dbca80f59a..5c704122f01 100644
--- a/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/Certificates.kt
+++ b/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/Certificates.kt
@@ -21,6 +21,7 @@ import javax.security.auth.x500.*
 import kotlin.time.*
 import kotlin.time.Duration
 import kotlin.time.Duration.Companion.days
+import kotlin.use
 
 internal val DEFAULT_PRINCIPAL = X500Principal("CN=localhost, OU=Kotlin, O=JetBrains, C=RU")
 private val DEFAULT_CA_PRINCIPAL = X500Principal("CN=localhostCA, OU=Kotlin, O=JetBrains, C=RU")
diff --git a/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/builders.kt b/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/builders.kt
index b8895edcb4c..ebd9ddf7694 100644
--- a/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/builders.kt
+++ b/ktor-network/ktor-network-tls/ktor-network-tls-certificates/jvm/src/io/ktor/network/tls/certificates/builders.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.network.tls.certificates
@@ -7,7 +7,6 @@ package io.ktor.network.tls.certificates
 import io.ktor.network.tls.*
 import io.ktor.network.tls.extensions.*
 import io.ktor.util.*
-import io.ktor.utils.io.core.*
 import java.io.*
 import java.net.*
 import java.security.*
diff --git a/ktor-server/ktor-server-cio/build.gradle.kts b/ktor-server/ktor-server-cio/build.gradle.kts
index c7b84585d68..454778782a3 100644
--- a/ktor-server/ktor-server-cio/build.gradle.kts
+++ b/ktor-server/ktor-server-cio/build.gradle.kts
@@ -18,11 +18,11 @@ kotlin.sourceSets {
             api(project(":ktor-server:ktor-server-core"))
             api(project(":ktor-client:ktor-client-cio"))
             api(project(":ktor-server:ktor-server-test-suites"))
+            api(project(":ktor-server:ktor-server-test-base"))
         }
     }
     jvmTest {
         dependencies {
-            api(project(":ktor-server:ktor-server-test-base"))
             api(project(":ktor-server:ktor-server-core", configuration = "testOutput"))
             api(libs.logback.classic)
             implementation(libs.kotlinx.coroutines.debug)
diff --git a/ktor-server/ktor-server-cio/jvmAndPosix/src/io/ktor/server/cio/backend/HttpServer.kt b/ktor-server/ktor-server-cio/jvmAndPosix/src/io/ktor/server/cio/backend/HttpServer.kt
index f24df8a15fd..3c811d9a72d 100644
--- a/ktor-server/ktor-server-cio/jvmAndPosix/src/io/ktor/server/cio/backend/HttpServer.kt
+++ b/ktor-server/ktor-server-cio/jvmAndPosix/src/io/ktor/server/cio/backend/HttpServer.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.server.cio.backend
 
@@ -11,8 +11,6 @@ import io.ktor.server.engine.*
 import io.ktor.server.engine.internal.*
 import io.ktor.util.logging.*
 import io.ktor.utils.io.*
-import io.ktor.utils.io.core.*
-import io.ktor.utils.io.errors.*
 import kotlinx.coroutines.*
 import kotlinx.io.IOException
 import kotlin.time.Duration.Companion.seconds
diff --git a/ktor-server/ktor-server-cio/jvmAndPosix/test/io/ktor/tests/server/cio/CIOEngineTest.kt b/ktor-server/ktor-server-cio/jvmAndPosix/test/io/ktor/tests/server/cio/CIOEngineTest.kt
index c2072804580..da08b330b05 100644
--- a/ktor-server/ktor-server-cio/jvmAndPosix/test/io/ktor/tests/server/cio/CIOEngineTest.kt
+++ b/ktor-server/ktor-server-cio/jvmAndPosix/test/io/ktor/tests/server/cio/CIOEngineTest.kt
@@ -2,6 +2,7 @@
  * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
+// ktlint-disable filename
 package io.ktor.tests.server.cio
 
 import io.ktor.client.statement.*
@@ -15,7 +16,6 @@ import io.ktor.server.response.*
 import io.ktor.server.routing.*
 import io.ktor.server.testing.suites.*
 import io.ktor.utils.io.*
-import io.ktor.utils.io.core.*
 import kotlin.test.*
 
 class CIOHttpServerTest : HttpServerCommonTestSuite<CIOApplicationEngine, CIOApplicationEngine.Configuration>(CIO) {
diff --git a/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt b/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt
index f38ce7ea430..6f8012d4664 100644
--- a/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt
+++ b/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.server.application
 
@@ -8,7 +8,6 @@ import io.ktor.server.routing.*
 import io.ktor.util.*
 import io.ktor.util.internal.*
 import io.ktor.util.pipeline.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 
 /**
@@ -230,7 +229,7 @@ public fun <A : Pipeline<*, PipelineCall>, B : Any, F : Any> A.uninstall(
 public fun <A : Pipeline<*, PipelineCall>, F : Any> A.uninstallPlugin(key: AttributeKey<F>) {
     val registry = attributes.getOrNull(pluginRegistryKey) ?: return
     val instance = registry.getOrNull(key) ?: return
-    if (instance is Closeable) {
+    if (instance is AutoCloseable) {
         instance.close()
     }
     registry.remove(key)
diff --git a/ktor-server/ktor-server-plugins/ktor-server-auth/common/test/io/ktor/tests/auth/SessionAuthTest.kt b/ktor-server/ktor-server-plugins/ktor-server-auth/common/test/io/ktor/tests/auth/SessionAuthTest.kt
index 0fcdefca394..c565add44a4 100644
--- a/ktor-server/ktor-server-plugins/ktor-server-auth/common/test/io/ktor/tests/auth/SessionAuthTest.kt
+++ b/ktor-server/ktor-server-plugins/ktor-server-auth/common/test/io/ktor/tests/auth/SessionAuthTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.tests.auth
@@ -14,7 +14,6 @@ import io.ktor.server.response.*
 import io.ktor.server.routing.*
 import io.ktor.server.sessions.*
 import io.ktor.server.testing.*
-import io.ktor.utils.io.core.*
 import kotlinx.serialization.*
 import kotlin.test.*
 
diff --git a/ktor-server/ktor-server-test-base/jsAndWasmShared/src/io/ktor/server/test/base/EngineTestBase.jsAndWasmShared.kt b/ktor-server/ktor-server-test-base/jsAndWasmShared/src/io/ktor/server/test/base/EngineTestBase.jsAndWasmShared.kt
index c688ed37db0..1c6d68b0d96 100644
--- a/ktor-server/ktor-server-test-base/jsAndWasmShared/src/io/ktor/server/test/base/EngineTestBase.jsAndWasmShared.kt
+++ b/ktor-server/ktor-server-test-base/jsAndWasmShared/src/io/ktor/server/test/base/EngineTestBase.jsAndWasmShared.kt
@@ -14,7 +14,6 @@ import io.ktor.server.engine.*
 import io.ktor.server.routing.*
 import io.ktor.server.testing.*
 import io.ktor.util.logging.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlin.coroutines.*
 import kotlin.time.Duration.Companion.seconds
diff --git a/ktor-server/ktor-server-test-base/posix/src/io/ktor/server/test/base/EngineTestBaseNix.kt b/ktor-server/ktor-server-test-base/posix/src/io/ktor/server/test/base/EngineTestBaseNix.kt
index 6e8967fe3ce..f888ea13575 100644
--- a/ktor-server/ktor-server-test-base/posix/src/io/ktor/server/test/base/EngineTestBaseNix.kt
+++ b/ktor-server/ktor-server-test-base/posix/src/io/ktor/server/test/base/EngineTestBaseNix.kt
@@ -17,7 +17,6 @@ import io.ktor.server.engine.*
 import io.ktor.server.routing.*
 import io.ktor.server.testing.*
 import io.ktor.util.logging.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 import kotlin.coroutines.*
 import kotlin.time.Duration.Companion.seconds
diff --git a/ktor-server/ktor-server-test-suites/common/src/io/ktor/server/testing/suites/HttpServerCommonTestSuite.kt b/ktor-server/ktor-server-test-suites/common/src/io/ktor/server/testing/suites/HttpServerCommonTestSuite.kt
index 2ab284af42d..183cb89576b 100644
--- a/ktor-server/ktor-server-test-suites/common/src/io/ktor/server/testing/suites/HttpServerCommonTestSuite.kt
+++ b/ktor-server/ktor-server-test-suites/common/src/io/ktor/server/testing/suites/HttpServerCommonTestSuite.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.server.testing.suites
@@ -33,6 +33,7 @@ import kotlin.coroutines.AbstractCoroutineContextElement
 import kotlin.coroutines.CoroutineContext
 import kotlin.test.*
 import kotlin.time.Duration.Companion.minutes
+import kotlin.use
 
 abstract class HttpServerCommonTestSuite<TEngine : ApplicationEngine, TConfiguration : ApplicationEngine.Configuration>(
     hostFactory: ApplicationEngineFactory<TEngine, TConfiguration>
diff --git a/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/HttpServerJvmTestSuite.kt b/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/HttpServerJvmTestSuite.kt
index 01c2e74bf27..87953596721 100644
--- a/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/HttpServerJvmTestSuite.kt
+++ b/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/HttpServerJvmTestSuite.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.server.testing.suites
@@ -25,6 +25,7 @@ import kotlin.coroutines.*
 import kotlin.test.*
 import kotlin.text.toByteArray
 import kotlin.time.Duration.Companion.seconds
+import kotlin.use
 
 abstract class HttpServerJvmTestSuite<TEngine : ApplicationEngine, TConfiguration : ApplicationEngine.Configuration>(
     hostFactory: ApplicationEngineFactory<TEngine, TConfiguration>
diff --git a/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/SustainabilityTestSuite.kt b/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/SustainabilityTestSuite.kt
index aac0cab8d0e..c939d333416 100644
--- a/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/SustainabilityTestSuite.kt
+++ b/ktor-server/ktor-server-test-suites/jvm/src/io/ktor/server/testing/suites/SustainabilityTestSuite.kt
@@ -35,6 +35,7 @@ import java.util.*
 import java.util.concurrent.*
 import java.util.concurrent.atomic.*
 import kotlin.test.*
+import kotlin.use
 
 abstract class SustainabilityTestSuite<TEngine : ApplicationEngine, TConfiguration : ApplicationEngine.Configuration>(
     hostFactory: ApplicationEngineFactory<TEngine, TConfiguration>
diff --git a/ktor-server/ktor-server-test-suites/jvmAndPosix/src/io/ktor/server/testing/suites/WebSocketEngineSuite.kt b/ktor-server/ktor-server-test-suites/jvmAndPosix/src/io/ktor/server/testing/suites/WebSocketEngineSuite.kt
index 30249e5b72e..f128bea5a70 100644
--- a/ktor-server/ktor-server-test-suites/jvmAndPosix/src/io/ktor/server/testing/suites/WebSocketEngineSuite.kt
+++ b/ktor-server/ktor-server-test-suites/jvmAndPosix/src/io/ktor/server/testing/suites/WebSocketEngineSuite.kt
@@ -26,6 +26,7 @@ import kotlin.test.*
 import kotlin.time.Duration.Companion.milliseconds
 import kotlin.time.Duration.Companion.minutes
 import kotlin.time.Duration.Companion.seconds
+import kotlin.use
 
 @OptIn(InternalAPI::class)
 abstract class WebSocketEngineSuite<TEngine : ApplicationEngine, TConfiguration : ApplicationEngine.Configuration>(
diff --git a/ktor-utils/jvm/src/io/ktor/util/cio/FileChannels.kt b/ktor-utils/jvm/src/io/ktor/util/cio/FileChannels.kt
index e673f52f114..c6b72d89991 100644
--- a/ktor-utils/jvm/src/io/ktor/util/cio/FileChannels.kt
+++ b/ktor-utils/jvm/src/io/ktor/util/cio/FileChannels.kt
@@ -1,12 +1,10 @@
 /*
- * Copyright 2014-2019 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package io.ktor.util.cio
 
-import io.ktor.util.*
 import io.ktor.utils.io.*
-import io.ktor.utils.io.core.*
 import io.ktor.utils.io.jvm.nio.*
 import kotlinx.coroutines.*
 import java.io.*