# UKF\_tractography\_vtkExtractSelectedPolyData error

**URL:** <https://discourse.slicer.org/t/ukf-tractography-vtkextractselectedpolydata-error/2124>\
**Category:** Support\
**Tags:** diffusion\
**Created:** [February 20, 2018, 1:58pm UTC](https://discourse.slicer.org/t/ukf-tractography-vtkextractselectedpolydata-error/2124 "2018-02-20T13:58:40Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ssousa](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@ssousa](https://discourse.slicer.org/u/ssousa)\
**Post date:** [February 20, 2018, 1:58pm UTC](https://discourse.slicer.org/t/ukf-tractography-vtkextractselectedpolydata-error/2124/1 "2018-02-20T13:58:40Z")

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When running UKF tractography the following error popup:  
ERROR: import port 0 of algorithm vtkExtractSelectedPolyDatalds (0x88e0fa0) has 0 connections but is not optional

 ![Descri%C3%A7aoErro](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/c/f/cf0bc383a7bc6667b4caeead7049be6f6cdd2698.png)  
Can you help me on this?  
Thank you in advance.  
Sónia S.

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**Author:** ![ihnorton](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ihnorton/32/9_2.png) [@ihnorton](https://discourse.slicer.org/u/ihnorton)\
**Post date:** [February 20, 2018, 9:25pm UTC](https://discourse.slicer.org/t/ukf-tractography-vtkextractselectedpolydata-error/2124/2 "2018-02-20T21:25:55Z")

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Hi Sónia,

Thanks for the report. I’ll check on the `vtkExtractSelectedPolyData error`. However, the underlying problem is the next one – the error message is “UKF Terminated with an unknown exception”. We’ve seen this happen sometimes with very large output track files. Would you mind to send information about

- your computer (looks like linux?)
- your dataset size
- what options you selected for UKFTractography. Please scroll up the Error Log to find the message that looks like the following, and copy it here (or screenshot):

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/7/7/77b7194ba6990385025c1d300cd3b61b5615709d.png)

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**Author:** ![ssousa](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@ssousa](https://discourse.slicer.org/u/ssousa)\
**Post date:** [February 20, 2018, 10:38pm UTC](https://discourse.slicer.org/t/ukf-tractography-vtkextractselectedpolydata-error/2124/3 "2018-02-20T22:38:07Z")

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Hi Isaiah,

Thanks a lot for your prompt attention to this subject.  
Please see below the answers to your queries.

 ![](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/2X/d/ded36c60b5fe97e71b1c16f5c477d49f34a158c6.png)

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<div class="post-metadata">

**Author:** ![ssousa](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@ssousa](https://discourse.slicer.org/u/ssousa)\
**Post date:** [February 20, 2018, 10:40pm UTC](https://discourse.slicer.org/t/ukf-tractography-vtkextractselectedpolydata-error/2124/4 "2018-02-20T22:40:21Z")

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your computer (looks like linux?) YES, THE COMPUTER IS A LINUX  
your dataset size - IT WAS JUST A SUBJECT!  
what options you selected for UKFTractography. Please scroll up the Error Log to find the message that looks like the following, and copy it here (or screenshot):PLEASE SEE ENCLOSED IMAGE WITH THIS INFORMATION

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<div class="post-metadata">

**Author:** ![ssousa](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@ssousa](https://discourse.slicer.org/u/ssousa)\
**Post date:** [February 23, 2018, 3:13pm UTC](https://discourse.slicer.org/t/ukf-tractography-vtkextractselectedpolydata-error/2124/5 "2018-02-23T15:13:24Z")

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Hi Isaiah,

Enclosed please find the shell print screen with the full description of the error. We don’t have more details. Can you help me in solving this?  
I thank you in advance for your help!  
Best  
Sónia

 ![Descri%C3%A7aoErro2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/2/e/2e4e6d2d84f309d7dc4b6bc756f0bb8f8c20170b.png)