https://intellij-support.jetbrains.com/hc/en-us/community/posts/360010054460-Intellij-doesn-t-recognize-the-file-
**Preferences | Editor | File Types | HTML**
Can you show the Preferences | Editor | File Types | HTML settings pane:
https://i.imgur.com/FA9tMfi.png
Does it help to reset settings via File | Manage IDE Settings | Restore Default Settings?

> go template使用.html文件时,不能识别因HTML关联了*.html,所以只能取消HTML,在go template重新关联.html才能使用

IDEA设置HTML文件中Vue语法提示
https://blog.51cto.com/lscl/5959218