# Possible Bug? system.tag.readBlocking

**URL:** <https://forum.inductiveautomation.com/t/possible-bug-system-tag-readblocking/60458>\
**Category:** Ignition\
**Created:** [June 7, 2022, 4:06pm UTC](https://forum.inductiveautomation.com/t/possible-bug-system-tag-readblocking/60458 "2022-06-07T16:06:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![levi.jacobs](https://avatars.discourse-cdn.com/v4/letter/l/dec6dc/32.png) [@levi.jacobs](https://forum.inductiveautomation.com/u/levi.jacobs)\
**Post date:** [June 7, 2022, 4:06pm UTC](https://forum.inductiveautomation.com/t/possible-bug-system-tag-readblocking/60458/1 "2022-06-07T16:06:58Z")

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I’m having trouble reading the UDT parent type of a UDT instance using the system.tag.readBlocking function. The old system.tag.read function still works, but system.tag.readBlocking returns None.

Here is some example code.

```auto
path_to_udt_instance = "[default]some_tag_path"

print system.tag.read(path_to_udt_instance+".udtParentType").value
print system.tag.readBlocking([path_to_udt_instance+".udtParentType"])[0].value

```

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<div class="post-metadata">

**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [June 7, 2022, 4:09pm UTC](https://forum.inductiveautomation.com/t/possible-bug-system-tag-readblocking/60458/2 "2022-06-07T16:09:11Z")

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Use `typeId`, not `udtParentType`. The legacy function is probably bridging the path over for you.

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<div class="post-metadata">

**Author:** ![levi.jacobs](https://avatars.discourse-cdn.com/v4/letter/l/dec6dc/32.png) [@levi.jacobs](https://forum.inductiveautomation.com/u/levi.jacobs)\
**Post date:** [June 7, 2022, 4:22pm UTC](https://forum.inductiveautomation.com/t/possible-bug-system-tag-readblocking/60458/3 "2022-06-07T16:22:51Z")

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Thank you!