# Ignition Client Crash When Opening Serial Port Post OS Upgrade

**URL:** <https://forum.inductiveautomation.com/t/ignition-client-crash-when-opening-serial-port-post-os-upgrade/112231>\
**Category:** Ignition\
**Tags:** scripting\
**Created:** [November 17, 2025, 3:38pm UTC](https://forum.inductiveautomation.com/t/ignition-client-crash-when-opening-serial-port-post-os-upgrade/112231 "2025-11-17T15:38:08Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Adil\_Hafiz](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@Adil\_Hafiz](https://forum.inductiveautomation.com/u/Adil_Hafiz)\
**Post date:** [November 17, 2025, 3:38pm UTC](https://forum.inductiveautomation.com/t/ignition-client-crash-when-opening-serial-port-post-os-upgrade/112231/1 "2025-11-17T15:38:08Z")

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In our Ignition application, we read data from a weight scale via the serial port. Recently, our IT department upgraded the Ignition client’s operating system to Windows 11. After the upgrade, the client fails to open the serial port using the command in the startup script and crashes without logging any errors in the server log.

We are currently using Ignition version 7.9.17. Below is the script that worked on Windows 10 but no longer functions on Windows 11. If I disable the last command `system.serial.openSerialPort(value)`, the client starts successfully.

if hostname == "XYZ":  
system.serial.configureSerialPort(  
port="COM3",  
bitRate=system.serial.BIT\_RATE\_19200,  
dataBits=system.serial.DATA\_BITS\_8,  
handshake=system.serial.HANDSHAKE\_NONE,  
hardwareFlowControl=0,  
parity=system.serial.PARITY\_NONE,  
stopBits=system.serial.STOP\_BITS\_2)  
value = 'COM3'  
system.serial.openSerialPort(value)

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<div class="post-metadata">

**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [November 17, 2025, 3:42pm UTC](https://forum.inductiveautomation.com/t/ignition-client-crash-when-opening-serial-port-post-os-upgrade/112231/2 "2025-11-17T15:42:03Z")

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The old serial library we used in 7.9 had a tendency to crash on newer versions of Windows than existed when it was released.

You could try 7.9.21 and see if it works, but otherwise you'll need to upgrade to 8.x where we replaced that old library with a different one.

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [November 17, 2025, 4:05pm UTC](https://forum.inductiveautomation.com/t/ignition-client-crash-when-opening-serial-port-post-os-upgrade/112231/3 "2025-11-17T16:05:04Z")

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Tip: If you are going to run unsupported old production software, don't upgrade any of the software around it. Someone should have objected to IT's arbitrary OS upgrade, at least until testing could reveal this side effect.