# Exception in ServerSocket: Socket::OperatorOverload \>\> causes control to restart

**URL:** <https://forum.universal-robots.com/t/exception-in-serversocket-socket-operatoroverload-causes-control-to-restart/42330>\
**Category:** Report a Bug\
**Created:** [February 26, 2026, 9:47pm UTC](https://forum.universal-robots.com/t/exception-in-serversocket-socket-operatoroverload-causes-control-to-restart/42330 "2026-02-26T21:47:23Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![thom.hendrixson](https://avatars.discourse-cdn.com/v4/letter/t/e19b73/32.png) [@thom.hendrixson](https://forum.universal-robots.com/u/thom.hendrixson)\
**Post date:** [February 26, 2026, 9:47pm UTC](https://forum.universal-robots.com/t/exception-in-serversocket-socket-operatoroverload-causes-control-to-restart/42330/1 "2026-02-26T21:47:23Z")

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Steps to reproduce:  
_Robot has been running more or less continuously for over a week._

Expected Behavior:  
_An exception would not be generated._

Actual Behavior:  
_An exception is generated in_ ServerSocket: Socket::OperatorOverload \>\> causing all sockets to be closed and URControl to restart.

Workaround Suggestion:  
_None_

Robot Serial Number:  
s/n: 20245500851 : UR5

Affected Version(s):  
URControl _5.18.0_

For this instance, the robot had been idle for about 30 minutes when the exception occurred. In another instance last month the robot had been idle for about 30 hours.

From the URControl log when the exception occurred.:

2026-02-25\_15:51:48:01741 06:58:43:021 INFO - Socket “XMLRPCClientSocket” object was destroyed.  
2026-02-25\_16:29:36:64093 07:36:31:723 WARNING - RTDETCPReceiver closed (exception caught): ServerSocket: Socket::recv() failed.  
2026-02-25\_16:29:36:64098 07:36:31:724 WARNING - TCPReceiver closed (CLIENTTYPE\_PRIMARY\_CLIENT) :: Exception caught: ServerSocket: Socket::OperatorOverload \>\> failed.  
2026-02-25\_16:29:36:64100 07:36:31:725 WARNING - TCPReceiver closed (CLIENTTYPE\_MATLAB\_CLIENT) :: Exception caught: ServerSocket: Socket::OperatorOverload \>\> failed.  
2026-02-25\_16:29:36:64102 07:36:31:725 WARNING - MultiTCPSender send: ServerSocket: Socket::sendall() failed.  
2026-02-25\_16:29:36:64911 07:36:31:733 WARNING - TCPReceiver closed (CLIENTTYPE\_SECONDARY\_CLIENT) :: Exception caught: ServerSocket: Socket::OperatorOverload \>\> failed.  
2026-02-25\_16:29:36:72172 07:36:31:807 ERROR - RTDETCPSender send: ServerSocket: Socket::sendall() failed.  
2026-02-25\_16:29:36:72983 07:36:31:816 WARNING - MultiTCPSender send: ServerSocket: Socket::sendall() failed.  
2026-02-25\_16:29:36:73796 07:36:31:823 INFO - Socket “CLIENTTYPE\_MATLAB\_CLIENT ClientSocket” disconnected by Socket::close()  
2026-02-25\_16:29:36:73800 07:36:31:823 INFO - Socket “CLIENTTYPE\_MATLAB\_CLIENT ClientSocket” object was destroyed.  
2026-02-25\_16:29:36:73802 07:36:31:823 INFO - Socket “CLIENTTYPE\_PRIMARY\_CLIENT ClientSocket” disconnected by Socket::close()  
2026-02-25\_16:29:36:73804 07:36:31:823 INFO - Socket “CLIENTTYPE\_PRIMARY\_CLIENT ClientSocket” object was destroyed.  
2026-02-25\_16:29:36:73806 07:36:31:823 INFO - TCPServer: RTDE client disconnected  
2026-02-25\_16:29:36:73808 07:36:31:823 INFO - Socket “CLIENTTYPE\_RTDE\_CLIENT ClientSocket” disconnected by Socket::close()  
2026-02-25\_16:29:36:73809 07:36:31:823 INFO - Socket “CLIENTTYPE\_RTDE\_CLIENT ClientSocket” object was destroyed.  
2026-02-25\_16:29:36:73811 07:36:31:823 INFO - Socket “CLIENTTYPE\_SECONDARY\_CLIENT ClientSocket” disconnected by Socket::close()  
2026-02-25\_16:29:36:73813 07:36:31:823 INFO - Socket “CLIENTTYPE\_SECONDARY\_CLIENT ClientSocket” object was destroyed.  
URControl::handler caught SIGTERM  
2026-02-25\_16:30:10:19104 07:37:05:273 INFO - tool\_mode changed from RUNNING to JOINT\_READY\_FOR\_POWER\_OFF  
2026-02-25\_16:30:10:19109 07:37:05:275 INFO - robot\_mode changed from ROBOT\_MODE\_RUNNING to ROBOT\_MODE\_POWER\_ON  
2026-02-25\_16:30:10:19111 07:37:05:276 WARNING - Runtime is too much behind (Runtime is not running, and not Blocked)  
2026-02-25\_16:30:10:19113 07:37:05:277 WARNING - Runtime is blocked, but runtime data queue is empty, trying to recover  
2026-02-25\_16:30:10:19115 07:37:05:279 INFO - SCB::logRobotStateChange: SafetyA robot state changed from ROBOT\_STATE\_RUNNING to ROBOT\_STATE\_PARKING  
2026-02-25\_16:30:10:19117 07:37:05:279 INFO - SCB::logRobotStateChange: SafetyB robot state changed from ROBOT\_STATE\_RUNNING to ROBOT\_STATE\_PARKING  
2026-02-25\_16:30:10:72379 07:37:05:813 INFO - SCB::logRobotStateChange: SafetyA robot state changed from ROBOT\_STATE\_PARKING to ROBOT\_STATE\_IDLE  
2026-02-25\_16:30:10:72387 07:37:05:813 INFO - SCB::logRobotStateChange: SafetyB robot state changed from ROBOT\_STATE\_PARKING to ROBOT\_STATE\_IDLE  
2026-02-25\_16:30:10:74003 07:37:05:829 INFO - SCB::logRobotStateChange: SafetyA robot state changed from ROBOT\_STATE\_IDLE to ROBOT\_STATE\_READY\_TO\_POWER\_OFF  
2026-02-25\_16:30:10:74009 07:37:05:829 INFO - SCB::logSafetyStateChange: SafetyA safety state changed from RUNNING to ROBOT\_OFF  
2026-02-25\_16:30:10:74011 07:37:05:829 INFO - SCB::logRobotStateChange: SafetyB robot state changed from ROBOT\_STATE\_IDLE to ROBOT\_STATE\_READY\_TO\_POWER\_OFF  
2026-02-25\_16:30:10:74013 07:37:05:829 INFO - SCB::logSafetyStateChange: SafetyB safety state changed from RUNNING to ROBOT\_OFF  
2026-02-25\_16:30:10:74822 07:37:05:837 INFO - SCB::logRobotStateChange: SafetyA robot state changed from ROBOT\_STATE\_READY\_TO\_POWER\_OFF to ROBOT\_STATE\_SHUTDOWN  
2026-02-25\_16:30:10:74828 07:37:05:837 INFO - SCB::logRobotStateChange: SafetyB robot state changed from ROBOT\_STATE\_READY\_TO\_POWER\_OFF to ROBOT\_STATE\_SHUTDOWN  
2026-02-25\_16:30:10:78870 07:37:05:871 INFO - robot\_mode changed from ROBOT\_MODE\_POWER\_ON to ROBOT\_MODE\_POWER\_OFF  
2026-02-25\_16:30:12:18560 07:37:05:892 INFO - TCPServer: RTDE client disconnected  
2026-02-25\_16:30:12:18566 07:37:05:892 INFO - Socket “CLIENTTYPE\_RTDE\_CLIENT ClientSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:18568 07:37:05:892 INFO - Socket “CLIENTTYPE\_RTDE\_CLIENT ClientSocket” object was destroyed.  
2026-02-25\_16:30:12:18570 07:37:05:892 INFO - Socket “CLIENTTYPE\_PRIMARY\_CLIENT ClientSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:18572 07:37:05:892 INFO - Socket “CLIENTTYPE\_PRIMARY\_CLIENT ClientSocket” object was destroyed.  
2026-02-25\_16:30:12:18573 07:37:05:892 INFO - Succeeded writing joint angles: [5.664114, 5.023640, 1.876840, 4.119736, 4.716408, 5.314355]  
2026-02-25\_16:30:12:19389 07:37:05:892 INFO - Socket “ModbusServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:19395 07:37:05:892 INFO - Socket “ModbusServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19397 07:37:05:892 INFO - Socket “PrimaryServerSocket” server with address 192.168.127.91:30001 connected to 192.168.127.11:54249 disconnected by Socket::close()  
2026-02-25\_16:30:12:19399 07:37:05:892 INFO - Socket “PrimaryServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19401 07:37:05:892 INFO - Socket “SecondaryServerSocket” server with address 192.168.127.91:30002 connected to 192.168.127.11:54250 disconnected by Socket::close()  
2026-02-25\_16:30:12:19403 07:37:05:892 INFO - Socket “SecondaryServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19405 07:37:05:892 INFO - Socket “InterpreterServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:19407 07:37:05:892 INFO - Socket “InterpreterServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19409 07:37:05:892 INFO - Socket “MATLABServerSocket” server with address 127.0.0.1:30003 connected to 127.0.0.1:52252 disconnected by Socket::close()  
2026-02-25\_16:30:12:19410 07:37:05:892 INFO - Socket “MATLABServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19412 07:37:05:892 INFO - Socket “RTDEServerSocket” server with address 127.0.0.1:30004 connected to 127.0.0.1:44770 disconnected by Socket::close()  
2026-02-25\_16:30:12:19414 07:37:05:892 INFO - Socket “RTDEServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19416 07:37:05:892 INFO - Socket “ReadOnlyPrimaryServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:19418 07:37:05:892 INFO - Socket “ReadOnlyPrimaryServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19420 07:37:05:892 INFO - Socket “ReadOnlySecondaryServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:19422 07:37:05:892 INFO - Socket “ReadOnlySecondaryServerSocket” object was destroyed.  
2026-02-25\_16:30:12:19423 07:37:05:892 INFO - Socket “ReadOnlyMATLABServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:19425 07:37:05:892 INFO - Socket “ReadOnlyMATLABServerSocket” object was destroyed.  
2026-02-25\_16:30:12:20237 07:37:05:892 INFO - WatchdogService::stopAllWatchdog()  
2026-02-25\_16:30:12:21048 07:37:05:896 INFO - Socket “RobotControlDataLoggerServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:21054 07:37:05:896 INFO - Socket “RobotControlDataLoggerServerSocket” object was destroyed.  
2026-02-25\_16:30:12:22666 07:37:05:906 INFO - Socket “DataScopeServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:22672 07:37:05:906 INFO - Socket “DataScopeServerSocket” object was destroyed.  
2026-02-25\_16:30:12:36389 07:37:06:048 INFO - Socket “FilesysServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:36394 07:37:06:048 INFO - Socket “FilesysServerSocket” object was destroyed.  
2026-02-25\_16:30:12:46888 07:37:06:152 INFO - Socket “BootloaderServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:46894 07:37:06:152 INFO - Socket “BootloaderServerSocket” object was destroyed.  
2026-02-25\_16:30:12:51736 07:37:06:199 INFO - Killing profisafebridge  
2026-02-25\_16:30:12:51741 07:37:06:199 INFO - Socket “ProfiSafeBridgeServerSocket” disconnected by Socket::close()  
2026-02-25\_16:30:12:51743 07:37:06:199 INFO - Socket “ProfiSafeBridgeServerSocket” object was destroyed.  
2026-02-25\_16:30:12:56587 07:37:06:251 INFO - Killing profisafebridge  
URControl::shutdown

I can provide the support file if needed (this reporting interface will not allow me to upload any files).

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<div class="post-metadata">

**Author:** ![osn](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/osn/32/2558_2.png) [@osn](https://forum.universal-robots.com/u/osn)\
**Post date:** [March 3, 2026, 12:50pm UTC](https://forum.universal-robots.com/t/exception-in-serversocket-socket-operatoroverload-causes-control-to-restart/42330/2 "2026-03-03T12:50:24Z")

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Hi Thom,

Please try this in the latest released software, SW 5.24. If it is still an issue, let us know.

Thanks for the report.

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**Author:** ![thom.hendrixson](https://avatars.discourse-cdn.com/v4/letter/t/e19b73/32.png) [@thom.hendrixson](https://forum.universal-robots.com/u/thom.hendrixson)\
**Post date:** [May 27, 2026, 4:33pm UTC](https://forum.universal-robots.com/t/exception-in-serversocket-socket-operatoroverload-causes-control-to-restart/42330/3 "2026-05-27T16:33:57Z")

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We were able to upgrade the customer to version 5.24 at the end of April. Unfortunately, the problem still exists. I will post the relevant information when I receive it from the customer.

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**Author:** ![thom.hendrixson](https://avatars.discourse-cdn.com/v4/letter/t/e19b73/32.png) [@thom.hendrixson](https://forum.universal-robots.com/u/thom.hendrixson)\
**Post date:** [May 28, 2026, 3:23pm UTC](https://forum.universal-robots.com/t/exception-in-serversocket-socket-operatoroverload-causes-control-to-restart/42330/4 "2026-05-28T15:23:11Z")

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[URControl.log.0.zip](https://forum.universal-robots.com/uploads/short-url/aogisy27a6zcZ2VwTpZomU61phq.zip) (142.4 KB)

I’ve attached the URControl.log file from the crash. The first socket exception happened at 22026-05-24\_06:35:407. The system had been idle for about 11 hours.

I will also note that after the support file was generated, the customer is unable to close the dialog that appears on the teach pendent indicating that the support file has been saved. When tapping the OK button in the dialog and tapping it, nothing happens and the cursor does not move to the button position. If they tap on other areas in the main window, the cursor moves to that spot as expected.

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<div class="post-metadata">

**Author:** ![thom.hendrixson](https://avatars.discourse-cdn.com/v4/letter/t/e19b73/32.png) [@thom.hendrixson](https://forum.universal-robots.com/u/thom.hendrixson)\
**Post date:** [July 23, 2026, 5:38pm UTC](https://forum.universal-robots.com/t/exception-in-serversocket-socket-operatoroverload-causes-control-to-restart/42330/5 "2026-07-23T17:38:37Z")

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This appears to be happening every couple of weeks. The latest time was last week. The error in the log appears to be similar, but there are other errors that were not present before that may be contributing to this issue.

[URControl.log.0.zip](https://forum.universal-robots.com/uploads/short-url/pMSrCZQA9fucX0oHbMZTLYgmJTt.zip) (229.8 KB)