diff --git a/core/src/main/java/hudson/ClassicPluginStrategy.java b/core/src/main/java/hudson/ClassicPluginStrategy.java
index bc00b2a0c9..6503d4b639 100644
--- a/core/src/main/java/hudson/ClassicPluginStrategy.java
+++ b/core/src/main/java/hudson/ClassicPluginStrategy.java
@@ -25,6 +25,8 @@ package hudson;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+
+import java.io.FileNotFoundException;
 import java.io.InputStream;
 import java.nio.file.Files;
 import java.nio.file.InvalidPathException;
@@ -110,11 +112,20 @@ public class ClassicPluginStrategy implements PluginStrategy {
 
     @Override public String getShortName(File archive) throws IOException {
         Manifest manifest;
+        if (!archive.exists()) {
+            throw new FileNotFoundException("Failed to load " + archive + ". The file does not exist");
+        } else if (!archive.isFile()) {
+            throw new FileNotFoundException("Failed to load " + archive + ". It is not a file");
+        }
+
         if (isLinked(archive)) {
             manifest = loadLinkedManifest(archive);
         } else {
             try (JarFile jf = new JarFile(archive, false)) {
                 manifest = jf.getManifest();
+            } catch (IOException ex) {
+                // Mention file name in the exception
+                throw new IOException("Failed to load " + archive, ex);
             }
         }
         return PluginWrapper.computeShortName(manifest, archive.getName());
diff --git a/core/src/main/java/hudson/model/Run.java b/core/src/main/java/hudson/model/Run.java
index 10ec9f6574..a3bc3375be 100644
--- a/core/src/main/java/hudson/model/Run.java
+++ b/core/src/main/java/hudson/model/Run.java
@@ -1554,6 +1554,10 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         
         RunListener.fireDeleted(this);
 
+        if (artifactManager != null) {
+            deleteArtifacts();
+        } // for StandardArtifactManager, deleting the whole build dir suffices
+
         synchronized (this) { // avoid holding a lock while calling plugin impls of onDeleted
         File tmp = new File(rootDir.getParentFile(),'.'+rootDir.getName());
         
diff --git a/core/src/main/java/hudson/slaves/SlaveComputer.java b/core/src/main/java/hudson/slaves/SlaveComputer.java
index c1b5166e71..15f106144a 100644
--- a/core/src/main/java/hudson/slaves/SlaveComputer.java
+++ b/core/src/main/java/hudson/slaves/SlaveComputer.java
@@ -39,6 +39,7 @@ import hudson.model.User;
 import hudson.remoting.Channel;
 import hudson.remoting.ChannelBuilder;
 import hudson.remoting.ChannelClosedException;
+import hudson.remoting.CommandTransport;
 import hudson.remoting.Launcher;
 import hudson.remoting.VirtualChannel;
 import hudson.security.ACL;
@@ -60,6 +61,8 @@ import jenkins.slaves.systemInfo.SlaveSystemInfo;
 import jenkins.util.SystemProperties;
 import org.acegisecurity.context.SecurityContext;
 import org.acegisecurity.context.SecurityContextHolder;
+import org.kohsuke.accmod.Restricted;
+import org.kohsuke.accmod.restrictions.Beta;
 import org.kohsuke.stapler.HttpRedirect;
 import org.kohsuke.stapler.HttpResponse;
 import org.kohsuke.stapler.QueryParameter;
@@ -69,6 +72,7 @@ import org.kohsuke.stapler.WebMethod;
 import org.kohsuke.stapler.interceptor.RequirePOST;
 
 import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
 import javax.annotation.OverridingMethodsMustInvokeSuper;
 import javax.servlet.ServletException;
 import java.io.File;
@@ -380,7 +384,15 @@ public class SlaveComputer extends Computer {
 
     private final Object channelLock = new Object();
 
-    public void setChannel(InputStream in, OutputStream out, TaskListener taskListener, Channel.Listener listener) throws IOException, InterruptedException {
+    /**
+     * Creates a {@link Channel} from the given stream and sets that to this agent.
+     *
+     * Same as {@link #setChannel(InputStream, OutputStream, OutputStream, Channel.Listener)}, but for
+     * {@link TaskListener}.
+     */
+    public void setChannel(@Nonnull InputStream in, @Nonnull OutputStream out,
+                           @Nonnull TaskListener taskListener,
+                           @CheckForNull Channel.Listener listener) throws IOException, InterruptedException {
         setChannel(in,out,taskListener.getLogger(),listener);
     }
 
@@ -403,7 +415,9 @@ public class SlaveComputer extends Computer {
      *      By the time this method is called, the cause of the termination is reported to the user,
      *      so the implementation of the listener doesn't need to do that again.
      */
-    public void setChannel(InputStream in, OutputStream out, OutputStream launchLog, Channel.Listener listener) throws IOException, InterruptedException {
+    public void setChannel(@Nonnull InputStream in, @Nonnull OutputStream out,
+                           @CheckForNull OutputStream launchLog,
+                           @CheckForNull Channel.Listener listener) throws IOException, InterruptedException {
         ChannelBuilder cb = new ChannelBuilder(nodeName,threadPoolForRemoting)
             .withMode(Channel.Mode.NEGOTIATE)
             .withHeaderStream(launchLog);
@@ -416,6 +430,39 @@ public class SlaveComputer extends Computer {
         setChannel(channel,launchLog,listener);
     }
 
+    /**
+     * Creates a {@link Channel} from the given Channel Builder and Command Transport.
+     * This method can be used to allow {@link ComputerLauncher}s to create channels not based on I/O streams.
+     *
+     * @param cb
+     *      Channel Builder.
+     *      To print launch logs this channel builder should have a Header Stream defined
+     *      (see {@link ChannelBuilder#getHeaderStream()}) in this argument or by one of {@link ChannelConfigurator}s.
+     * @param commandTransport
+     *      Command Transport
+     * @param listener
+     *      Gets a notification when the channel closes, to perform clean up. Can be {@code null}.
+     *      By the time this method is called, the cause of the termination is reported to the user,
+     *      so the implementation of the listener doesn't need to do that again.
+     * @since 2.127
+     */
+    @Restricted(Beta.class)
+    public void setChannel(@Nonnull ChannelBuilder cb,
+                           @Nonnull CommandTransport commandTransport,
+                           @CheckForNull Channel.Listener listener) throws IOException, InterruptedException {
+        for (ChannelConfigurator cc : ChannelConfigurator.all()) {
+            cc.onChannelBuilding(cb,this);
+        }
+
+        OutputStream headerStream = cb.getHeaderStream();
+        if (headerStream == null) {
+            LOGGER.log(Level.WARNING, "No header stream defined when setting channel for computer {0}. " +
+                    "Launch log won't be printed", this);
+        }
+        Channel channel = cb.build(commandTransport);
+        setChannel(channel, headerStream, listener);
+    }
+
     /**
      * Shows {@link Channel#classLoadingCount}.
      * @since 1.495
@@ -509,14 +556,18 @@ public class SlaveComputer extends Computer {
 
     /**
      * Sets up the connection through an existing channel.
-     * @param channel the channel to use; <strong>warning:</strong> callers are expected to have called {@link ChannelConfigurator} already
+     * @param channel the channel to use; <strong>warning:</strong> callers are expected to have called {@link ChannelConfigurator} already.
+     * @param launchLog Launch log. If not {@code null}, will receive launch log messages
+     * @param listener Channel event listener to be attached (if not {@code null})
      * @since 1.444
      */
-    public void setChannel(Channel channel, OutputStream launchLog, Channel.Listener listener) throws IOException, InterruptedException {
+    public void setChannel(@Nonnull Channel channel,
+                           @CheckForNull OutputStream launchLog,
+                           @CheckForNull Channel.Listener listener) throws IOException, InterruptedException {
         if(this.channel!=null)
             throw new IllegalStateException("Already connected");
 
-        final TaskListener taskListener = new StreamTaskListener(launchLog);
+        final TaskListener taskListener = launchLog != null ? new StreamTaskListener(launchLog) : TaskListener.NULL;
         PrintStream log = taskListener.getLogger();
 
         channel.setProperty(SlaveComputer.class, this);
diff --git a/core/src/main/java/hudson/util/Iterators.java b/core/src/main/java/hudson/util/Iterators.java
index 74d82950dc..8d93d72262 100644
--- a/core/src/main/java/hudson/util/Iterators.java
+++ b/core/src/main/java/hudson/util/Iterators.java
@@ -23,6 +23,7 @@
  */
 package hudson.util;
 
+import com.google.common.annotations.Beta;
 import com.google.common.base.Predicates;
 import com.google.common.collect.ImmutableList;
 
@@ -35,6 +36,9 @@ import java.util.AbstractList;
 import java.util.Arrays;
 import java.util.Set;
 import java.util.HashSet;
+import javax.annotation.Nonnull;
+import org.kohsuke.accmod.Restricted;
+import org.kohsuke.accmod.restrictions.NoExternalUse;
 
 /**
  * Varios {@link Iterator} implementations.
@@ -403,4 +407,20 @@ public class Iterators {
     public interface CountingPredicate<T> {
         boolean apply(int index, T input);
     }
+
+    /**
+     * Similar to {@link com.google.common.collect.Iterators#skip} except not {@link Beta}.
+     * @param iterator some iterator
+     * @param count a nonnegative count
+     */
+    @Restricted(NoExternalUse.class)
+    public static void skip(@Nonnull Iterator<?> iterator, int count) {
+        if (count < 0) {
+            throw new IllegalArgumentException();
+        }
+        while (iterator.hasNext() && count-- > 0) {
+            iterator.next();
+        }
+    }
+
 }
diff --git a/core/src/main/java/hudson/util/RunList.java b/core/src/main/java/hudson/util/RunList.java
index d9b8adb7dc..bdc9cb61f4 100644
--- a/core/src/main/java/hudson/util/RunList.java
+++ b/core/src/main/java/hudson/util/RunList.java
@@ -150,7 +150,7 @@ public class RunList<R extends Run> extends AbstractList<R> {
     public List<R> subList(int fromIndex, int toIndex) {
         List<R> r = new ArrayList<R>();
         Iterator<R> itr = iterator();
-        Iterators.skip(itr,fromIndex);
+        hudson.util.Iterators.skip(itr, fromIndex);
         for (int i=toIndex-fromIndex; i>0; i--) {
             r.add(itr.next());
         }
diff --git a/core/src/main/java/hudson/util/StreamTaskListener.java b/core/src/main/java/hudson/util/StreamTaskListener.java
index bd2b6dc87e..b2b2e4fd62 100644
--- a/core/src/main/java/hudson/util/StreamTaskListener.java
+++ b/core/src/main/java/hudson/util/StreamTaskListener.java
@@ -44,6 +44,9 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.kohsuke.stapler.framework.io.WriterOutputStream;
 
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
+
 // TODO: AbstractTaskListener is empty now, but there are dependencies on that e.g. Ruby Runtime - JENKINS-48116)
 // The change needs API deprecation policy or external usages cleanup.
 
@@ -56,7 +59,9 @@ import org.kohsuke.stapler.framework.io.WriterOutputStream;
  * @author Kohsuke Kawaguchi
  */
 public class StreamTaskListener extends AbstractTaskListener implements TaskListener, Closeable {
+    @Nonnull
     private PrintStream out;
+    @CheckForNull
     private Charset charset;
 
     /**
@@ -66,15 +71,15 @@ public class StreamTaskListener extends AbstractTaskListener implements TaskList
      *      or use {@link #fromStdout()} or {@link #fromStderr()}.
      */
     @Deprecated
-    public StreamTaskListener(PrintStream out) {
+    public StreamTaskListener(@Nonnull PrintStream out) {
         this(out,null);
     }
 
-    public StreamTaskListener(OutputStream out) {
+    public StreamTaskListener(@Nonnull OutputStream out) {
         this(out,null);
     }
 
-    public StreamTaskListener(OutputStream out, Charset charset) {
+    public StreamTaskListener(@Nonnull OutputStream out, @CheckForNull Charset charset) {
         try {
             if (charset == null)
                 this.out = (out instanceof PrintStream) ? (PrintStream)out : new PrintStream(out, false);
@@ -87,18 +92,18 @@ public class StreamTaskListener extends AbstractTaskListener implements TaskList
         }
     }
 
-    public StreamTaskListener(File out) throws IOException {
+    public StreamTaskListener(@Nonnull File out) throws IOException {
         this(out,null);
     }
 
-    public StreamTaskListener(File out, Charset charset) throws IOException {
+    public StreamTaskListener(@Nonnull File out, @CheckForNull Charset charset) throws IOException {
         // don't do buffering so that what's written to the listener
         // gets reflected to the file immediately, which can then be
         // served to the browser immediately
         this(Files.newOutputStream(asPath(out)), charset);
     }
 
-    private static Path asPath(File out) throws IOException {
+    private static Path asPath(@Nonnull File out) throws IOException {
         try {
             return out.toPath();
         } catch (InvalidPathException e) {
@@ -115,7 +120,7 @@ public class StreamTaskListener extends AbstractTaskListener implements TaskList
      * @throws IOException if the file could not be opened.
      * @since 1.651
      */
-    public StreamTaskListener(File out, boolean append, Charset charset) throws IOException {
+    public StreamTaskListener(@Nonnull File out, boolean append, @CheckForNull Charset charset) throws IOException {
         // don't do buffering so that what's written to the listener
         // gets reflected to the file immediately, which can then be
         // served to the browser immediately
@@ -127,7 +132,7 @@ public class StreamTaskListener extends AbstractTaskListener implements TaskList
         );
     }
 
-    public StreamTaskListener(Writer w) throws IOException {
+    public StreamTaskListener(@Nonnull Writer w) throws IOException {
         this(new WriterOutputStream(w));
     }
 
@@ -155,7 +160,7 @@ public class StreamTaskListener extends AbstractTaskListener implements TaskList
 
     @Override
     public Charset getCharset() {
-        return charset;
+        return charset != null ? charset : Charset.defaultCharset();
     }
 
     private void writeObject(ObjectOutputStream out) throws IOException {
diff --git a/core/src/main/java/jenkins/widgets/HistoryPageFilter.java b/core/src/main/java/jenkins/widgets/HistoryPageFilter.java
index 269f5e44fc..521ace8b79 100644
--- a/core/src/main/java/jenkins/widgets/HistoryPageFilter.java
+++ b/core/src/main/java/jenkins/widgets/HistoryPageFilter.java
@@ -24,7 +24,6 @@
 package jenkins.widgets;
 
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Iterators;
 import hudson.model.AbstractBuild;
 import hudson.model.Job;
 import hudson.model.ParameterValue;
@@ -32,6 +31,7 @@ import hudson.model.ParametersAction;
 import hudson.model.Queue;
 import hudson.model.Run;
 import hudson.search.UserSearchProperty;
+import hudson.util.Iterators;
 import hudson.widgets.HistoryWidget;
 
 import javax.annotation.Nonnull;
diff --git a/core/src/test/java/hudson/util/IteratorsTest.java b/core/src/test/java/hudson/util/IteratorsTest.java
index 679df76a65..4236ca359d 100644
--- a/core/src/test/java/hudson/util/IteratorsTest.java
+++ b/core/src/test/java/hudson/util/IteratorsTest.java
@@ -32,6 +32,7 @@ import java.util.Iterator;
 import java.util.List;
 
 import org.junit.Test;
+import org.jvnet.hudson.test.Issue;
 
 /**
  * @author Kohsuke Kawaguchi
@@ -77,9 +78,27 @@ public class IteratorsTest {
         assertEquals("[]", com.google.common.collect.Iterators.toString(Iterators.limit(asList(1,2,4,6).iterator(), EVEN)));
     }
 
-    public static final CountingPredicate<Integer> EVEN = new CountingPredicate<Integer>() {
-        public boolean apply(int index, Integer input) {
-            return input % 2 == 0;
-        }
-    };
+    public static final CountingPredicate<Integer> EVEN = (index, input) -> input % 2 == 0;
+
+    @Issue("JENKINS-51779")
+    @Test
+    public void skip() {
+        List<Integer> lst = Iterators.sequence(1, 4);
+        Iterator<Integer> it = lst.iterator();
+        Iterators.skip(it, 0);
+        assertEquals("[1, 2, 3]", com.google.common.collect.Iterators.toString(it));
+        it = lst.iterator();
+        Iterators.skip(it, 1);
+        assertEquals("[2, 3]", com.google.common.collect.Iterators.toString(it));
+        it = lst.iterator();
+        Iterators.skip(it, 2);
+        assertEquals("[3]", com.google.common.collect.Iterators.toString(it));
+        it = lst.iterator();
+        Iterators.skip(it, 3);
+        assertEquals("[]", com.google.common.collect.Iterators.toString(it));
+        it = lst.iterator();
+        Iterators.skip(it, 4);
+        assertEquals("[]", com.google.common.collect.Iterators.toString(it));
+    }
+
 }
diff --git a/pom.xml b/pom.xml
index aeba985b12..7b6592c7a0 100644
--- a/pom.xml
+++ b/pom.xml
@@ -107,7 +107,7 @@ THE SOFTWARE.
     <maven-war-plugin.version>3.0.0</maven-war-plugin.version> <!-- JENKINS-47127 bump when 3.2.0 is out. Cf. MWAR-407 -->
 
     <!-- Bundled Remoting version -->
-    <remoting.version>3.20</remoting.version>
+    <remoting.version>3.21</remoting.version>
     <!-- Minimum Remoting version, which is tested for API compatibility -->
     <remoting.minimum.supported.version>2.60</remoting.minimum.supported.version>
 
diff --git a/test/src/test/java/hudson/model/RunTest.java b/test/src/test/java/hudson/model/RunTest.java
index 92cbef2081..7150aac135 100644
--- a/test/src/test/java/hudson/model/RunTest.java
+++ b/test/src/test/java/hudson/model/RunTest.java
@@ -23,19 +23,30 @@
  */
 package hudson.model;
 
+import hudson.FilePath;
+import hudson.Launcher;
+import hudson.tasks.ArtifactArchiver;
+import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+import jenkins.model.ArtifactManager;
+import jenkins.model.ArtifactManagerConfiguration;
+import jenkins.model.ArtifactManagerFactory;
+import jenkins.model.ArtifactManagerFactoryDescriptor;
+import jenkins.model.Jenkins;
+import jenkins.util.VirtualFile;
 import static org.junit.Assert.*;
 import org.junit.Rule;
 import org.junit.Test;
 import org.jvnet.hudson.test.Issue;
 import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.TestExtension;
+import org.kohsuke.stapler.DataBoundConstructor;
 
-/**
- * @author Kohsuke Kawaguchi
- */
 public class RunTest  {
 
     @Rule public JenkinsRule j = new JenkinsRule();
@@ -73,4 +84,33 @@ public class RunTest  {
         assertEquals(Run.KeepLogBuildBadge.class, badgeActions.get(0).getClass());
     }
 
+    @Issue("JENKINS-51819")
+    @Test public void deleteArtifactsCustom() throws Exception {
+        ArtifactManagerConfiguration.get().getArtifactManagerFactories().add(new Mgr.Factory());
+        FreeStyleProject p = j.createFreeStyleProject();
+        j.jenkins.getWorkspaceFor(p).child("f").write("", null);
+        p.getPublishersList().add(new ArtifactArchiver("f"));
+        FreeStyleBuild b = j.buildAndAssertSuccess(p);
+        b.delete();
+        assertTrue(Mgr.deleted.get());
+    }
+    private static final class Mgr extends ArtifactManager {
+        static final AtomicBoolean deleted = new AtomicBoolean();
+        @Override public boolean delete() throws IOException, InterruptedException {
+            return !deleted.getAndSet(true);
+        }
+        @Override public void onLoad(Run<?, ?> build) {}
+        @Override public void archive(FilePath workspace, Launcher launcher, BuildListener listener, Map<String, String> artifacts) throws IOException, InterruptedException {}
+        @Override public VirtualFile root() {
+            return VirtualFile.forFile(Jenkins.get().getRootDir()); // irrelevant
+        }
+        public static final class Factory extends ArtifactManagerFactory {
+            @DataBoundConstructor public Factory() {}
+            @Override public ArtifactManager managerFor(Run<?, ?> build) {
+                return new Mgr();
+            }
+            @TestExtension("deleteArtifactsCustom") public static final class DescriptorImpl extends ArtifactManagerFactoryDescriptor {}
+        }
+    }
+
 }