Fallout 4’s location is straightforward, but modded restoration is not. A base .fos file can reference content from plugins, and F4SE can add a paired cosave. The safest archive therefore includes the full save directory plus enough information to rebuild the mod environment. A failed load after moving PCs is not automatically evidence of file corruption; missing plugins, changed load order, or an absent cosave can be the real cause.
Which storefront context matters
Documented Fallout 4 PC launchers/storefronts: Steam, Microsoft Store / Xbox app. The standard Documents path is the primary Windows reference. Microsoft Store packaging can differ, so locate the active edition before restoring a file. The active storefront/account should be identified before any restore because cloud and local storage may not use the same path or container across editions.
Documented cloud behavior
Cloud behavior depends on storefront. OneDrive may also synchronize the Documents tree if Windows folder backup is enabled. Cloud synchronization is useful for continuity, but it can also turn a restore into a conflict-resolution event. Let synchronization settle before making a manual backup, and keep an offline copy outside any folder monitored by the launcher or operating-system sync service.
Local save roots still matter
The researched local save boundary is Windows: %USERPROFILE%DocumentsMy GamesFallout4Saves | Linux / Steam Play: Steam Play: <SteamLibrary-folder>/steamapps/compatdata/377160/pfx/; the known file or folder pattern is *.fos
*.f4se (when created by F4SE). A cloud-enabled game still has concrete local data involved in ordinary play, and that local context is what you need when identifying which copy was modified most recently.
Avoid accidental overwrite loops
Copy the complete Saves directory. On F4SE setups, keep matching .fos and .f4se files together and record the installed mod/load-order state. When restoring, close the game and launcher, preserve both the current local copy and the backup you want to test, then place the intended data in the matching profile/storefront location. Do not repeatedly open the game between different copies without noting which side the cloud client selected.
Compatibility and conflict checks
A clean base-game save and a heavily modded save have very different restoration requirements even if both use .fos. If progress disappears or rolls back, If an apparently valid save crashes on load after migration, verify missing plugins and script-extender dependencies before replacing more files. Also check whether Documents is redirected by OneDrive. Resolve identity/path/cloud questions first. A cloud conflict is not proof that the save itself is corrupt, and a successful upload is not proof that files from another storefront are compatible.
Verification context: The standard Windows and Steam Play save locations were reviewed against current PCGamingWiki coverage. Format notes distinguish base .fos saves from optional F4SE cosaves.