404 error for /public/static just uploaded files only in production mode

[haw0k]

My project is based on NextJS 9 custom server. Custom server is Express v4.

I upload files through the multipart form to the server into /public/static/ folder by multer.

In production mode I always receive response with 404 code for GET-requests to just uploaded files.
After server restart I receive response with 200 code for all previously uploaded files and 404 code for new uploads only.

This issue does not exist in developer mode.

Problem is not present only if
server.js contained:
const nextApp = nextjs({ dev });
and server launch command is:
$ nodemon server.js

Versions tested:

• OS: Ubuntu 18.04 and Windows 7 x64
• Version of Next.js: 9.4.4 and 9.5.3
• Version of Node.js: 10.20.1 and 12.18.4

github project page