java net SocketException Connection reset

Question

I am getting the following error trying to read from a socket  I m doing a readInt   on that InputStream  and I am getting this error  Perusing the documentation this suggests that the client part of the connection closed the connection  In this scenario  I am the server   I have access to the client log files and it is not closing the connection  and in fact its log files suggest I am closing the connection  So does anybody have an idea why this is happening  What else to check for  Does this arise when there are local resources that are perhaps reaching thresholds     I do note that I have the following line   socket setSoTimeout 10000     just prior to the readInt    There is a reason for this  long story   but just curious  are there circumstances under which this might lead to the indicated error  I have the server running in my IDE  and I happened to leave my IDE stuck on a breakpoint  and I then noticed the exact same errors begin appearing in my own logs in my IDE   Anyway  just mentioning it  hopefully not a red herring   -

User · Answer

In my experience  I often encounter the following situations    If you work in a corporate company  contact the network and security team  Because in requests made to external services  it may be necessary to give permission for the relevant endpoint  Another issue is that the SSL certificate may have expired on the server where your application is running

User · Answer

There are several possible causes    The other end has deliberately reset the connection  in a way which I will not document here  It is rare  and generally incorrect  for application software to do this  but it is not unknown for commercial software  More commonly  it is caused by writing to a connection that the other end has already closed normally  In other words an application protocol error  It can also be caused by closing a socket when there is unread data in the socket receive buffer  In Windows   software caused connection abort   which is not the same as  connection reset   is caused by network problems sending from your end  There s a Microsoft knowledge base article about this

User · Answer

Whenever I have had odd issues like this  I usually sit down with a tool like WireShark and look at the raw data being passed back and forth  You might be surprised where things are being disconnected  and you are only being notified when you try and read

User · Answer

I had the same error  I found the solution for problem now  The problem was client program was finishing before server read the streams

User · Answer

Connection reset simply means that a TCP RST was received  This happens when your peer receives data that it can t process  and there can be various reasons for that   The simplest is when you close the socket  and then write more data on the output stream  By closing the socket  you told your peer that you are done talking  and it can forget about your connection  When you send more data on that stream anyway  the peer rejects it with an RST to let you know it isn t listening   In other cases  an intervening firewall or even the remote host itself might  forget  about your TCP connection  This could happen if you don t send any data for a long time  2 hours is a common time-out   or because the peer was rebooted and lost its information about active connections  Sending data on one of these defunct connections will cause a RST too     Update in response to additional information    Take a close look at your handling of the SocketTimeoutException  This exception is raised if the configured timeout is exceeded while blocked on a socket operation  The state of the socket itself is not changed when this exception is thrown  but if your exception handler closes the socket  and then tries to write to it  you ll be in a connection reset condition  setSoTimeout   is meant to give you a clean way to break out of a read   operation that might otherwise block forever  without doing dirty things like closing the socket from another thread

User · Answer

Connection reset simply means that a TCP RST was received  This happens when your peer receives data that it can t process  and there can be various reasons for that   The simplest is when you close the socket  and then write more data on the output stream  By closing the socket  you told your peer that you are done talking  and it can forget about your connection  When you send more data on that stream anyway  the peer rejects it with an RST to let you know it isn t listening   In other cases  an intervening firewall or even the remote host itself might  forget  about your TCP connection  This could happen if you don t send any data for a long time  2 hours is a common time-out   or because the peer was rebooted and lost its information about active connections  Sending data on one of these defunct connections will cause a RST too     Update in response to additional information    Take a close look at your handling of the SocketTimeoutException  This exception is raised if the configured timeout is exceeded while blocked on a socket operation  The state of the socket itself is not changed when this exception is thrown  but if your exception handler closes the socket  and then tries to write to it  you ll be in a connection reset condition  setSoTimeout   is meant to give you a clean way to break out of a read   operation that might otherwise block forever  without doing dirty things like closing the socket from another thread

User · Answer

There are several possible causes    The other end has deliberately reset the connection  in a way which I will not document here  It is rare  and generally incorrect  for application software to do this  but it is not unknown for commercial software  More commonly  it is caused by writing to a connection that the other end has already closed normally  In other words an application protocol error  It can also be caused by closing a socket when there is unread data in the socket receive buffer  In Windows   software caused connection abort   which is not the same as  connection reset   is caused by network problems sending from your end  There s a Microsoft knowledge base article about this

User · Answer

Check your server s Java version  Happened to me because my Weblogic 10 3 6 was on JDK 1 7 0 75 which was on TLSv1  The rest endpoint I was trying to consume was shutting down anything below TLSv1 2    By default Weblogic was trying to negotiate the strongest shared protocol  See details here  Issues with setting https protocols System Property for HTTPS connections   I added verbose SSL logging to identify the supported TLS  This indicated TLSv1 was being used for the handshake  -Djavax net debug ssl handshake verbose keymanager trustmanager -Djava security debug access stack  I resolved this by pushing the feature out to our JDK8-compatible product  JDK8 defaults to TLSv1 2  For those restricted to JDK7  I also successfully tested a workaround for Java 7 by upgrading to TLSv1 2  I used this answer  How to enable TLS 1 2 in Java 7

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I also had this problem with a Java program trying to send a command on a server via SSH  The problem was with the machine executing the Java code  It didn t have the permission to connect to the remote server  The write   method was doing alright  but the read   method was throwing a java net SocketException  Connection reset  I fixed this problem with adding the client SSH key to the remote server known keys

User · Answer

Embarrassing to say it  but when I had this problem  it was simply a mistake that I was closing the connection before I read all the data   In cases with small strings being returned  it worked  but that was probably due to the whole response was buffered  before I closed it   In cases of longer amounts of text being returned  the exception was thrown  since more then a buffer was coming back   You might check for this oversight   Remember opening a URL is like a file  be sure to close it  release the connection  once it has been fully read

User · Answer

Whenever I have had odd issues like this  I usually sit down with a tool like WireShark and look at the raw data being passed back and forth  You might be surprised where things are being disconnected  and you are only being notified when you try and read

User · Answer

Check your server s Java version  Happened to me because my Weblogic 10 3 6 was on JDK 1 7 0 75 which was on TLSv1  The rest endpoint I was trying to consume was shutting down anything below TLSv1 2    By default Weblogic was trying to negotiate the strongest shared protocol  See details here  Issues with setting https protocols System Property for HTTPS connections   I added verbose SSL logging to identify the supported TLS  This indicated TLSv1 was being used for the handshake  -Djavax net debug ssl handshake verbose keymanager trustmanager -Djava security debug access stack  I resolved this by pushing the feature out to our JDK8-compatible product  JDK8 defaults to TLSv1 2  For those restricted to JDK7  I also successfully tested a workaround for Java 7 by upgrading to TLSv1 2  I used this answer  How to enable TLS 1 2 in Java 7

User · Answer

You should inspect full trace very carefully  I ve a server socket application and fixed a java net SocketException  Connection reset case  In my case it happens while reading from a clientSocket Socket object which is closed its connection because of some reason   Network lost firewall or application crash or intended close  Actually I was re-establishing connection when I got an error while reading from this Socket object  Socket clientSocket   ServerSocket accept    is   new BufferedReader new InputStreamReader clientSocket getInputStream      int readed   is read       WHERE ERROR STARTS      The interesting thing is for my JAVA Socket if a client connects to my ServerSocket and close its connection without sending anything is read   is being called repeatedly It seems because of being in an infinite while loop for reading from this socket you try to read from a closed connection  If you use something like below for read operation  while true      Receive       Then you get a stackTrace something like below on and on java net SocketException  Socket is closed     at java net ServerSocket accept ServerSocket java 494   What I did is just closing ServerSocket and renewing my connection and waiting for further incoming client connections String Receive   throws Exception   try                                  int readed   is read                     catch Exception e            tryReConnect            logit      etc              This reestablises my connection for unknown client socket losts private void tryReConnect                         try                               ServerSocket close                      empty my old lost connection and let it get by garbage col  immediately                  clientSocket null                  System gc                      Wait a new client Socket connection and address this to my local variable                 clientSocket  ServerSocket accept       Waiting for another Connection                 System out println  quot Connection established    quot                 catch  Exception e                    String message  quot ReConnect not successful  quot  e getMessage                    logit     etc                             I couldn t find another way because as you see from below image you can t understand whether connection is lost or not without a try and catch  because everything seems right   I got this snapshot while I was getting Connection reset continuously

User · Answer

Connection reset simply means that a TCP RST was received  This happens when your peer receives data that it can t process  and there can be various reasons for that   The simplest is when you close the socket  and then write more data on the output stream  By closing the socket  you told your peer that you are done talking  and it can forget about your connection  When you send more data on that stream anyway  the peer rejects it with an RST to let you know it isn t listening   In other cases  an intervening firewall or even the remote host itself might  forget  about your TCP connection  This could happen if you don t send any data for a long time  2 hours is a common time-out   or because the peer was rebooted and lost its information about active connections  Sending data on one of these defunct connections will cause a RST too     Update in response to additional information    Take a close look at your handling of the SocketTimeoutException  This exception is raised if the configured timeout is exceeded while blocked on a socket operation  The state of the socket itself is not changed when this exception is thrown  but if your exception handler closes the socket  and then tries to write to it  you ll be in a connection reset condition  setSoTimeout   is meant to give you a clean way to break out of a read   operation that might otherwise block forever  without doing dirty things like closing the socket from another thread

User · Answer

Whenever I have had odd issues like this  I usually sit down with a tool like WireShark and look at the raw data being passed back and forth  You might be surprised where things are being disconnected  and you are only being notified when you try and read

User · Answer

Connection reset simply means that a TCP RST was received  This happens when your peer receives data that it can t process  and there can be various reasons for that   The simplest is when you close the socket  and then write more data on the output stream  By closing the socket  you told your peer that you are done talking  and it can forget about your connection  When you send more data on that stream anyway  the peer rejects it with an RST to let you know it isn t listening   In other cases  an intervening firewall or even the remote host itself might  forget  about your TCP connection  This could happen if you don t send any data for a long time  2 hours is a common time-out   or because the peer was rebooted and lost its information about active connections  Sending data on one of these defunct connections will cause a RST too     Update in response to additional information    Take a close look at your handling of the SocketTimeoutException  This exception is raised if the configured timeout is exceeded while blocked on a socket operation  The state of the socket itself is not changed when this exception is thrown  but if your exception handler closes the socket  and then tries to write to it  you ll be in a connection reset condition  setSoTimeout   is meant to give you a clean way to break out of a read   operation that might otherwise block forever  without doing dirty things like closing the socket from another thread

User · Answer

I had this problem with a SOA system written in Java   I was running both the client and the server on different physical machines and they worked fine for a long time  then those nasty connection resets appeared in the client log and there wasn t anything strange in the server log   Restarting both client and server didn t solve the problem   Finally we discovered that the heap on the server side was rather full so we increased the memory available to the JVM  problem solved   Note that there was no OutOfMemoryError in the log  memory was just scarce  not exhausted

User · Answer

Whenever I have had odd issues like this  I usually sit down with a tool like WireShark and look at the raw data being passed back and forth  You might be surprised where things are being disconnected  and you are only being notified when you try and read

User · Answer

You should inspect full trace very carefully  I ve a server socket application and fixed a java net SocketException  Connection reset case  In my case it happens while reading from a clientSocket Socket object which is closed its connection because of some reason   Network lost firewall or application crash or intended close  Actually I was re-establishing connection when I got an error while reading from this Socket object  Socket clientSocket   ServerSocket accept    is   new BufferedReader new InputStreamReader clientSocket getInputStream      int readed   is read       WHERE ERROR STARTS      The interesting thing is for my JAVA Socket if a client connects to my ServerSocket and close its connection without sending anything is read   is being called repeatedly It seems because of being in an infinite while loop for reading from this socket you try to read from a closed connection  If you use something like below for read operation  while true      Receive       Then you get a stackTrace something like below on and on java net SocketException  Socket is closed     at java net ServerSocket accept ServerSocket java 494   What I did is just closing ServerSocket and renewing my connection and waiting for further incoming client connections String Receive   throws Exception   try                                  int readed   is read                     catch Exception e            tryReConnect            logit      etc              This reestablises my connection for unknown client socket losts private void tryReConnect                         try                               ServerSocket close                      empty my old lost connection and let it get by garbage col  immediately                  clientSocket null                  System gc                      Wait a new client Socket connection and address this to my local variable                 clientSocket  ServerSocket accept       Waiting for another Connection                 System out println  quot Connection established    quot                 catch  Exception e                    String message  quot ReConnect not successful  quot  e getMessage                    logit     etc                             I couldn t find another way because as you see from below image you can t understand whether connection is lost or not without a try and catch  because everything seems right   I got this snapshot while I was getting Connection reset continuously

User · Answer

Embarrassing to say it  but when I had this problem  it was simply a mistake that I was closing the connection before I read all the data   In cases with small strings being returned  it worked  but that was probably due to the whole response was buffered  before I closed it   In cases of longer amounts of text being returned  the exception was thrown  since more then a buffer was coming back   You might check for this oversight   Remember opening a URL is like a file  be sure to close it  release the connection  once it has been fully read

User · Answer

I had the same error  I found the solution for problem now  The problem was client program was finishing before server read the streams

User · Answer

In my experience  I often encounter the following situations    If you work in a corporate company  contact the network and security team  Because in requests made to external services  it may be necessary to give permission for the relevant endpoint  Another issue is that the SSL certificate may have expired on the server where your application is running

User · Answer

I also had this problem with a Java program trying to send a command on a server via SSH  The problem was with the machine executing the Java code  It didn t have the permission to connect to the remote server  The write   method was doing alright  but the read   method was throwing a java net SocketException  Connection reset  I fixed this problem with adding the client SSH key to the remote server known keys

User · Answer

I had this problem with a SOA system written in Java   I was running both the client and the server on different physical machines and they worked fine for a long time  then those nasty connection resets appeared in the client log and there wasn t anything strange in the server log   Restarting both client and server didn t solve the problem   Finally we discovered that the heap on the server side was rather full so we increased the memory available to the JVM  problem solved   Note that there was no OutOfMemoryError in the log  memory was just scarce  not exhausted

[java] java.net.SocketException: Connection reset

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