respond 404 while get a file of i18n dir

the file is already existed,I have searched existed issues and checkout to the master branch,The problem has not disappeared，so I have to wirte a handler to handle static files of i18n by myself。
Is this a work in progress?or i should add some items in profile。
Sorry for my poor fluent English

Start by reproducing the 404 for an existing file in the i18n directory on the master branch, then trace the static-file handling entry point. Confirm whether the file is served correctly without a custom handler and document the relevant configuration or missing behavior.

Written by the indexing model from the issue text.