Hello

By default, Posts app and the other content related apps don't have breatcrumb and it cannot be easily added (activated) via Studio. But some groundwork is already available. So, you need to do the following:

1. I added some code in the version which allows to add breadcrumbs in content related apps without customizations in core files. It will be released in the next update. So, you may add it in your UNA right now if you have access to files and necessary knowledges.
https://github.com/unaio/una/issues/2265

2. You need to copy breadcrumb.html file from modules/boonex/forum/template/ folder in modules/boonex/posts/template/ one, in case of the Posts app.

3. You need to go to Studio -> Developer app -> Pages -> select Posts -> select View Post page and add Service block in necessary position. Use the following code in the Code field

array (
'module' => 'bx_posts',
'method' => 'entity_breadcrumb',
)

Fill in the other mandatory fields and save the block.

4. You are welcome to test your Breadcrumb on some View Post page. 

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Best Regards
Anton