# Upgrading to Bootstrap 5

**URL:** <https://forum.dotvvm.com/t/upgrading-to-bootstrap-5/301>\
**Category:** Discussion in English\
**Tags:** bootstrap5\
**Created:** [March 6, 2025, 11:48pm UTC](https://forum.dotvvm.com/t/upgrading-to-bootstrap-5/301 "2025-03-06T23:48:39Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![edoms06](https://forum.dotvvm.com/letter_avatar_proxy/v4/letter/e/b38774/32.png) [@edoms06](https://forum.dotvvm.com/u/edoms06)\
**Post date:** [March 6, 2025, 11:48pm UTC](https://forum.dotvvm.com/t/upgrading-to-bootstrap-5/301/1 "2025-03-06T23:48:39Z")

</div>

We recently upgraded from Bootstrap 4 to Bootstrap 5 in our DotVVM application. After making this change and updating our configuration using:

```auto
config.AddBootstrap5Configuration();

```

we started encountering the following error:

```auto
Attribute value of type 'CommandBindingExpression<Delegate>' is not supported. 
Please convert the value to string, e.g., by using ToString().

```

This issue did not occur when using Bootstrap 4, and it only started after switching to Bootstrap 5. It seems that some DotVVM bindings, particularly command bindings, are no longer being recognized correctly when used in attributes.

Could you provide guidance on whether this is a known issue with the Bootstrap 5 configuration in DotVVM? Additionally, is there a recommended approach to resolve this without having to refactor existing bindings?

Any insights would be greatly appreciated.

Thank you.

---

<div class="post-metadata">

**Author:** ![edoms06](https://forum.dotvvm.com/letter_avatar_proxy/v4/letter/e/b38774/32.png) [@edoms06](https://forum.dotvvm.com/u/edoms06)\
**Post date:** [March 10, 2025, 11:46pm UTC](https://forum.dotvvm.com/t/upgrading-to-bootstrap-5/301/2 "2025-03-10T23:46:04Z")

</div>

I think the issue was the TabControl. **ActiveTabChanged** has been removed. Any idea how to achieve this now? Thanks!