# Change parameters in legacy tracker

**URL:** <https://forum.opencv.org/t/change-parameters-in-legacy-tracker/5172>\
**Category:** Python\
**Tags:** tracking\
**Created:** [September 12, 2021, 2:41pm UTC](https://forum.opencv.org/t/change-parameters-in-legacy-tracker/5172 "2021-09-12T14:41:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Mor](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/mor/32/2686_2.png) [@Mor](https://forum.opencv.org/u/Mor)\
**Post date:** [September 12, 2021, 2:41pm UTC](https://forum.opencv.org/t/change-parameters-in-legacy-tracker/5172/1 "2021-09-12T14:41:03Z")

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Hi,  
I’m using opencv version 4.5.3 which support legacy trackers.  
I’m trying to change parameters in the same way that I did with the regular tracker (older opencv version),picture attached.  
 ![image](https://us1.discourse-cdn.com/flex020/uploads/opencv/original/2X/5/5b856451247402bd26e963f460fa132bcdf6083d.png)  
but when I use the legacy tracker:  
tracker = cv2.legacy.TrackerCSRT\_create(param\_handler)  
I get the error:  
SystemError: returned NULL without setting an error

I would really appreciate your help,  
Thanks!

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**Author:** ![berak](https://avatars.discourse-cdn.com/v4/letter/b/85f322/32.png) [@berak](https://forum.opencv.org/u/berak)\
**Post date:** [September 12, 2021, 3:37pm UTC](https://forum.opencv.org/t/change-parameters-in-legacy-tracker/5172/2 "2021-09-12T15:37:18Z")

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please never post images of code anywhere …

and no idea why, but there is only a `create()` [function without any arguments](https://docs.opencv.org/master/d7/d8f/classcv_1_1legacy_1_1TrackerCSRT.html#a3c5ae96951e36434274d8c616de8850e) for this in python (same problem for all legacy trackers, btw !)