The correct approach in this kind of scenario is to upload the file ...

Without tracking tools nobody knows which pages are broken. How to find all pages in all Wikisource instances where is required uploading new files? They can only be found by chance.

Case above is just an example. This can be any abstract file with any abstract reason of deletion. After deletion of file, the text is no longer displayed even though text exists.

In T361438#9683859, @Charlie_WMDE wrote:

Hey @Butko this was most liekly due to an outage we were experiencing this weekend (related ticket here T361551). I just tried it and it works again so i'm closing the ticket. If the problem persists for you, feel free to reopen it. thanks!

yes, it works now