Baldur's Gate 3 Mod Mismatch or Data Warning: Isolate Before Cleanup

Decide whether this is a party mismatch or a PC install warning

These symptoms need different checks. A modded party that cannot load points first to cross-player content parity. A launcher Data Mismatch warning is a local-install branch; Larian describes a generated list of unexpected files and the locations of relevant mod data. A game update can expose old mod conflicts, but the warning alone does not prove which file caused it.

References: Larian Studios: Official Mod Support · Larian Studios: Mod Issues

Make a modded multiplayer set comparable

Larian's official support guidance says every player in a modded multiplayer session needs exactly the same mods and versions. Similar names are not enough: compare the selected mod list and version shown in each player's in-game manager. Keep the list stable while testing so the outcome can be attributed to one change.

1. Ask every player to note the installed game build and the exact enabled mod names/versions from the in-game Mod Manager.
2. Compare the complete lists. Add missing mods, remove extras, and update a mod when its Installed tab shows Update; all players should match before launching.
3. If the party still fails, have all players disable mods and attempt the same lobby once. If unmodded works, re-enable a small, agreed set only after checking mod updates and dependencies.
4. If unmodded also fails, keep the result separate from a mod diagnosis and capture the exact error, platform, build and host/join role for Larian support.
5. Do not overwrite or share a campaign save as a test. Keep a copy of valuable saves before changing mod state.

References: Larian Studios: Cross-play — Hosting or Joining a Game · Larian Studios: Official Mod Support · Larian Studios: Mod Issues

PC-only branch: inspect a Data Mismatch report safely

Larian's Mod Issues FAQ says a launcher mismatch warning creates a text file listing unexpected install files and files in the Mods folder. It names a Steam-style filename beginning steam_<Current.Version.Number>_alteredFiles.txt or a similarly named galaxy_ file for GOG. This is an evidence source—not a verdict that every listed file is malicious or safe to delete.

1. Before editing files, make a separate backup of the affected profile and saves. Confirm you can identify the correct game profile and installation; do not copy a path from another user's PC blindly.
2. For Windows PC, open %LocalAppData%\Larian Studios\Launcher\Cache and locate the alteredFiles text file whose name matches your launcher/current version (steam_... or galaxy_...). Save a copy of the report for reference.
3. Larian's FAQ identifies the install Data\Mods and Data\Public folders and the profile modsettings.lsx file as possible third-party-mod remnants. Compare those locations against the warning and your own install history before considering cleanup.
4. If cleanup is needed, remove only files you can identify and only after backup; use the launcher or official support if uncertain. Then verify the game files with the store launcher and test once before restoring mods.
5. If the warning persists, provide the exact filename, launcher, build and report to Larian support. Redact your Windows account name and any private paths before posting publicly.

References: Larian Studios: Mod Issues

Limits and escalation

The official Mod Issues FAQ's third-party file cleanup and alteredFiles paths are Windows-PC guidance. The official Mod Support page describes the in-game manager and supported mods, but that does not establish that every mod is compatible with every save or platform. Do not delete profile data on console, Mac or an unverified installation based on this section.

References: Larian Studios: Official Mod Support · Larian Studios: Mod Issues · Larian Studios Forums

Before you play

• For multiplayer, each person compared the complete enabled mod list and exact versions.
• I tested with mods disabled only as an isolation step, not as proof of a culprit.
• For PC cleanup, I backed up saves/profile data and read the named log before changing files.
• I kept platform-specific PC file paths away from console/Mac instructions.
• My correction/report contains the game build and reproducible symptom, not credentials.

Frequently asked questions

Sources & revision notes

Editorial revision: November 5, 2026; not a gameplay test date. The reference notes identify source limits and version differences.

1. Larian Studios: Official Mod Support (Official)

   Developer support reference checked November 5, 2026. For modded multiplayer it requires the same mods and versions for each player and points to the in-game Mod Manager's Installed tab for updates. Toolkit availability and cross-save version notes are not treated here as current rollout guarantees.

2. Larian Studios: Mod Issues (Official)

   Developer support reference checked November 5, 2026. It suggests disabling supported mods to isolate an issue and gives PC-specific steps for third-party-mod/data-mismatch cases. File cleanup is potentially destructive; the guide adds a backup-first caution and does not claim to inspect or repair a reader's files.

3. Larian Studios: Cross-play — Hosting or Joining a Game (Official)

   Developer support instructions checked November 5, 2026. They describe linking a Larian account, enabling cross-play, adding Larian-account friends, opening Multiplayer > Cross-Play, and enabling cross-play on an existing save. The article lists PC, Xbox, PS5, Mac and GOG platform references. No invite, lobby, account or multiplayer session was tested.

4. Larian Studios Forums (Official)

   Publisher-hosted community forum. Posts are user-submitted and are not verified by GamerWin; match platform, game build and mod state, and redact account or save identifiers before sharing.