Steps:

1. Go to Content/ Content structure.
2. Create new content which contains RichText field, e.g. Folder.
3. Add embed to RTE.
4. Publish.

Actual result:
Error occurs

 Unknown "fos_httpcache_tag" function. [in vendor/ezsystems/ezplatform-richtext/src/bundle/Resources/views/RichText/embed/content.html.twig:10]