Maybe default Socket timeout on your system is not high enough. Could you provide the full stacktrace?

Installing Plugins/Upgrades

Preparation
Checking internet connectivity
Checking update center connectivity
Success
jenkins.war
Failure -
hudson.util.IOException2: Failed to download from http://updates.jenkins-ci.org/download/war/2.14/jenkins.war (redirected to: http://ftp-chi.osuosl.org/pub/jenkins/war/2.14/jenkins.war)
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1153)
at hudson.model.UpdateCenter$DownloadJob._run(UpdateCenter.java:1650)
at hudson.model.UpdateCenter$DownloadJob.run(UpdateCenter.java:1624)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at hudson.remoting.AtmostOneThreadExecutor$Worker.run(AtmostOneThreadExecutor.java:110)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.SocketTimeoutException: Read timed out
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection$10.run(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection$10.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.net.www.protocol.http.HttpURLConnection.getChainedException(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1105)
... 6 more
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(Unknown Source)
at java.net.SocketInputStream.read(Unknown Source)
at java.net.SocketInputStream.read(Unknown Source)
at java.io.BufferedInputStream.fill(Unknown Source)
at java.io.BufferedInputStream.read1(Unknown Source)
at java.io.BufferedInputStream.read(Unknown Source)
at sun.net.www.http.HttpClient.parseHTTPHeader(Unknown Source)
at sun.net.www.http.HttpClient.parseHTTP(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getHeaderField(Unknown Source)
at java.net.URLConnection.getHeaderFieldLong(Unknown Source)
at java.net.URLConnection.getContentLengthLong(Unknown Source)
at java.net.URLConnection.getContentLength(Unknown Source)
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1104)
... 6 more

facing below issue, please suggest is this relevant to this JIRA:

hudson.util.IOException2: Failed to download from http://updates.jenkins-ci.org/download/plugins/git-client/2.2.1/git-client.hpi (redirected to: http://ftp.tsukuba.wide.ad.jp/software/jenkins/plugins/git-client/2.2.1/git-client.hpi)
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1172)
at hudson.model.UpdateCenter$DownloadJob._run(UpdateCenter.java:1678)
at hudson.model.UpdateCenter$InstallationJob._run(UpdateCenter.java:1876)
at hudson.model.UpdateCenter$DownloadJob.run(UpdateCenter.java:1652)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at hudson.remoting.AtmostOneThreadExecutor$Worker.run(AtmostOneThreadExecutor.java:110)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.net.SocketTimeoutException: Read timed out
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at sun.net.www.protocol.http.HttpURLConnection$10.run(HttpURLConnection.java:1926)

I can repro after un upgrade from Jenkins 2.35 to Jenkins 2.42.

Can't update plugins either.

java.net.SocketTimeoutException: connect timed out
	at java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
	at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:589)
	at sun.net.NetworkClient.doConnect(NetworkClient.java:175)

Hello all,

We had have the same Issue today in Jenkins Version 2.121.1, I searched a workarround and uninstalled the Plugin but timeout still exist, even on a new installation.

It would be nice, if you could give us a work arround to install the plugin, without an timeout issue.

Our Jenkins is running in a Debian Server.

Kind Regards
Ben

Hi, I'm joining ben3d question.