Error with embed

Hello,
You can use the white list to prevent from controlling some routes.

#2 Yes I tried it with this route /embed/preview/full_html and it doesn't work always crashes

You should use the route's name, not the path.

#4 Ah I understand but how can I get the name of that route

Try this one : entity_embed.preview

If you're encountering difficulties reviewing embedding images in CKEditor, you might want to exclude the 'media.filter.preview' route.