# Validation Error - Cannot create unknown type

**URL:** <https://forum.uipath.com/t/validation-error-cannot-create-unknown-type/717497>\
**Category:** Studio\
**Tags:** help, validation-error, question, studio\
**Created:** [February 6, 2024, 6:35am UTC](https://forum.uipath.com/t/validation-error-cannot-create-unknown-type/717497 "2024-02-06T06:35:25Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![HongYee\_Gan](https://sea2.discourse-cdn.com/uipath/user_avatar/forum.uipath.com/hongyee_gan/32/404096_2.png) [@HongYee\_Gan](https://forum.uipath.com/u/HongYee_Gan)\
**Post date:** [February 6, 2024, 6:35am UTC](https://forum.uipath.com/t/validation-error-cannot-create-unknown-type/717497/1 "2024-02-06T06:35:25Z")

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Hi, I have this UiPath studio robot. It was running fine until recently (2024 onwards). There was an error when i try to run directly by clicking the running button.

**error:**  
Inbox\_Email\_Extraction.xaml: Cannot create unknown type ‘{[http://schemas.microsoft.com/netfx/2009/xaml/activities](http://schemas.microsoft.com/netfx/2009/xaml/activities)}Variable({clr-namespace:System.Collections.Generic;assembly=System.Private.CoreLib}List({clr-namespace:NewTestRegex;assembly=NewTestRegex.Core}PermitDetails))’.

 ![486dabf6-86cc-4b3f-95dc-a2703ce94892](https://global.discourse-cdn.com/uipath/original/4X/a/c/e/ace3ee1aa87d1d43d375fb0dbaec12fd1850ca43.png)

However, the error did not show up when I run from the main sequence (3 dots), then click ‘continue’ after that.

sorry that I am a new user, unable to show more than 1 image.

Need help me to solve this issue. Many Thanks.

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<div class="post-metadata">

**Author:** ![Yoichi](https://sea2.discourse-cdn.com/uipath/user_avatar/forum.uipath.com/yoichi/32/523754_2.png) [@Yoichi](https://forum.uipath.com/u/Yoichi)\
**Post date:** [February 6, 2024, 6:47am UTC](https://forum.uipath.com/t/validation-error-cannot-create-unknown-type/717497/2 "2024-02-06T06:47:23Z")

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Hi,

It seems there is unresolved activity in Inbox\_Email\_Extraction.xaml.  
For now, can you check what activity error caused in Inbox\_Email\_Extraction.xaml and if there is an erro regarding dependencies in Project panel?

Regards,

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<div class="post-metadata">

**Author:** ![HongYee\_Gan](https://sea2.discourse-cdn.com/uipath/user_avatar/forum.uipath.com/hongyee_gan/32/404096_2.png) [@HongYee\_Gan](https://forum.uipath.com/u/HongYee_Gan)\
**Post date:** [February 6, 2024, 9:03am UTC](https://forum.uipath.com/t/validation-error-cannot-create-unknown-type/717497/3 "2024-02-06T09:03:08Z")

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There is no error on dependencies. All dependencies were up to date. The error came at the start, before running any activity. Its like checking for validation. See image.

 ![Screenshot (2)](https://global.discourse-cdn.com/uipath/original/4X/c/f/7/cf7c8c234291fdb86b937f452ae60a4707d5b5a7.png)