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.
Prepare the source PC
On the source system, identify the actual Fallout 4 save root: Windows: %USERPROFILE%DocumentsMy GamesFallout4Saves | Linux / Steam Play: Steam Play: <SteamLibrary-folder>/steamapps/compatdata/377160/pfx/. The expected file/folder pattern is *.fos
*.f4se (when created by F4SE). Close the game, let the active launcher finish writing and synchronizing, then make a complete offline copy rather than transferring a file that may still be open.
Preserve storefront and profile identity
Documented 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. A transfer between two PCs is simplest when both systems use the same storefront/account/profile context. If the destination uses a different store or container, treat that as a migration problem rather than an ordinary restore.
Move the complete save boundary
Copy the complete Saves directory. On F4SE setups, keep matching .fos and .f4se files together and record the installed mod/load-order state. Put the copied data on the destination only after confirming the destination save path. If the game creates a new empty save first, keep that new folder as another backup so you can compare structures and revert.
Handle cloud sync deliberately
Cloud behavior depends on storefront. OneDrive may also synchronize the Documents tree if Windows folder backup is enabled. Decide whether the local transferred copy or cloud copy should be authoritative before launching the game. If possible, preserve both. After the transferred save loads correctly, make a fresh in-game save and let the launcher synchronize normally.
Check compatibility before blaming the transfer
Base Fallout 4 saves use .fos. F4SE-enabled installations can create companion .f4se cosaves; preserving only one side of a modded save may remove script-extender state. Compatibility note: A clean base-game save and a heavily modded save have very different restoration requirements even if both use .fos. If the destination does not see the transferred progress, 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. Verify game edition/version, store, profile IDs, redirected folders, and mod/DLC dependencies before editing the save itself.
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.