Cannot select blog post category anymore : error 404 View not found [name, type, prefix]: category, html, Administrator

Hello,
I was trying to create a new menu item to show a list of one category of blog posts, it is configured that way :
- menu item type : Gridbox/Category
- app : blog
Then when I want to select the category for the field "Category" insted of the usual list, I have an error message saying : "error 404 View not found [name, type, prefix]: category, html, Administrator" (see the screen shot enclosed).

Can you tell me if this can be corrected ?

Thank you.

Manès

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