Hi @johnsmith
That folder path is actually fine. The backoffice uses a cache buster, which is the hash you’re seeing in the URLs. It’s a virtual path segment based on the Umbraco version, so you won’t find a matching physical folder under /umbraco/backoffice.
The 404s suggest your browser has cached the old 17.2.2 entry point, which references files that no longer exist in 17.4.0. Try a hard refresh (Ctrl+F5), an incognito window or a different browser.
If that doesn’t fix it, check whether a CDN or proxy (e.g. Cloudflare) is caching /umbraco/* and purge it. There’s a recent thread on this here:
Justin