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Fixed in 2022.2.X

Duplicate in 2021.3.X



Found in





Issue ID




[UIToolkit] ArgumentOutOfRangeException is thrown when adding/removing elements from a List in the Inspector

UI Toolkit


How to reproduce:
1. Open the attached "case_1418688" project
2. Open the "SampleScene" Scene
3. Select the "Repro" GameObject in the Hierarchy
4. Click the "+" button under the "Component -> Colors" List in the Inspector to add a new element to that List

Expected result: A new element is added to the "Colors" List without any errors
Actual result: A new element is added to the "Colors" List with the "ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection." error thrown in the Console log

Reproducible with: 2021.3.1f1, 2022.1.0a16, 2022.1.0b16, 2022.2.0a3
Not reproducible with: 2022.1.0a1, 2022.1.0a15, 2022.2.0a4, 2022.2.0a10
Couldn't test with: 2019.4.38f1, 2020.3.33f1 (the project isn't compatible)

- The error is thrown after adding/removing the 7-8th and more element
- In some versions, the "SerializedProperty[INDEX] has disappeared!" error is thrown instead, where INDEX is the element position index in the List

  1. Resolution Note (fix version 2022.2):

    Fixed in 2022.2.0a4

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