01What Preloader.dll is, and what the error means
A failed to find Preloader.dll error in r2modman is a loader problem, not a mod problem. Community loaders such as BepInEx use a preloader or doorstop component to inject plugin DLLs into the game at runtime, and Preloader.dll is one of the loader's own files. When the game reports it missing, the loader could not start at all, which is why every installed plugin also appears broken. Nothing about the individual mods has been tested yet. Fix the loader installation and its version first, and only look at plugin code once the loader starts cleanly.
- Preloader.dll belongs to the loader, not to a mod.
- A missing preloader means no plugin could have loaded.
- Fix the loader layer before testing individual mods.
02Reset the game installation on the affected profile
The repair action for loader and black-screen failures is Settings → Debugging → Reset ⟨game⟩ installation, which older builds labelled “Preloader fix”. It deletes the contents of the game folder and asks Steam to re-validate the game, so take a profile export from Settings → Profile → Export profile before you run it. Wait until Steam has finished validating before you close anything or launch the game. Afterwards launch with Start modded and check whether the error is gone before changing anything else. If the game instead opens to a black screen, the loader started, which is real progress.
- Select the affected profile before running anything.
- Settings → Debugging → Reset ⟨game⟩ installation (older builds: “Preloader fix”).
- It clears the game folder, so take an export first: Settings → Profile → Export profile.
03Match the loader to the exact game build
A preloader that worked last week usually fails because the game changed underneath it. Game updates can break doorstop and preloader injection until the loader or the community core pack is updated for the new build. Check the game's version, check which loader version the profile has installed, and compare both with the requirement stated by the game's community. Installing the newest loader blindly is also risky, because a loader built for a newer game build can fail against an older one. Keep the working game and loader versions recorded so the pair can be restored.
- Note the game build and the loader version in the profile.
- Compare both with the community's stated requirement.
- Do not assume the newest loader suits every game build.
04Confirm the loader files are in the active profile
Profiles are separate, so a loader installed in one profile does not exist in another. If you switched profiles or imported a code, the active profile may contain mods but no loader files at all. Open the profile folder from Settings and confirm the loader's files, including the preloader component, are present, then check that the loader appears enabled in the Installed tab. A profile that lists mods as installed while its loader folder is missing is a profile-level problem and will reproduce on every single launch.
- Each profile keeps its own loader files.
- Open the profile folder from Settings and check they exist.
- Confirm the loader is enabled in the Installed tab.
05Check quarantine for the named DLL
Security software can remove one DLL from an otherwise intact loader, and the game then reports the file as missing even though the manager installed it correctly. Open Windows Security → Virus & threat protection → Protection history (or run windowsdefender: from Win + R), filter on Quarantined items, and search for the exact filename from the error. Check its version and size before restoring anything — and add an exclusion afterwards under Virus & threat protection → Manage settings → Exclusions, because Defender will quarantine the same file again on its next scan otherwise. If the file was quarantined, add an exception for the game folder or for that specific file rather than excluding an entire drive, then re-apply the loader by launching the profile again with Start modded, so the deployed loader files are written back. Restoring a file that was flagged for a genuine reason is worse than reinstalling the loader.
- Search the quarantine history for the exact DLL name.
- Verify filename, version, and size before restoring a file.
- Prefer a narrow exception over excluding a whole drive.
06Rebuild the loader in a clean profile
When the loader still fails, remove the variables. Create a new profile for the same game, install only the community-required loader or core pack from the Online tab, and use Start modded with no other packages present. If the loader starts there, the original profile is damaged or contains a conflicting package, and you can import the old profile's code into a fresh profile and reinstall in batches. If a loader-only profile fails as well, the cause is the loader version, the game build, or the platform rather than anything you installed.
- New profile, loader or core pack only.
- Import the old profile code into a fresh profile afterwards.
- A loader-only failure points at version or platform, not mods.
07Tell a loader error apart from a plugin error
The first error in the log identifies the layer. A preloader, doorstop, or injection message means the loader never handed control to your plugins, so mod versions are irrelevant at that point. An error naming a plugin DLL, a missing type, or a dependency assembly means the loader worked and one specific package failed. Once you see plugin-level errors, disable the named package, launch again, and read the new first error. Identify the layer before choosing a fix. Reinstalling the loader while a plugin is failing costs time and changes nothing about the broken package.
- Preloader or doorstop message: the loader layer failed.
- Plugin DLL or missing type named: the loader worked.
- Fix the layer the first error actually names.
✦ Frequently asked questions
Common questions, answered directly.
Where do I download Preloader.dll?
You do not download it separately. It ships as part of the loader or community core pack that r2modman installs from the Online tab for that game. Downloading a loose DLL of the same name from elsewhere gives you an unverified file and a version nobody can confirm matches your game build.
Is Preloader.dll malicious?
It is a normal component of community loaders such as BepInEx and is the part that injects plugin DLLs into the game. That does not make every file with that name trustworthy. Check the source, and let the manager install the loader so the version matches the game build.
Will resetting the game installation remove my mods?
It leaves the selected profile's package list alone, but it does delete the contents of the game folder, which includes the loader files the manager had deployed there — they are written back the next time you launch that profile with Start modded. Take a profile export first, run it on the profile that has the problem, and let Steam finish validating without interrupting it.
The game shows a black screen after the fix. Now what?
A black screen usually means the loader started but the game did not finish initialising. Run Settings → Debugging → Reset ⟨game⟩ installation again and let Steam's validation complete, then launch with Start modded and read the first exception in the loader log rather than the last — Settings → Debugging → Copy log to clipboard copies it out for you.
Does this error mean a mod is broken?
No. A preloader message points at the loader layer, which runs before any plugin loads, so no mod has been tested yet. Only an error that names a plugin DLL or a missing dependency tells you something about a specific mod, and only then is disabling a package the right next step.
Work the checks in order and stop at the first one that changes the symptom. That step is the cause; the checks after it only matter if the symptom survives.
Next: change one thing at a time, relaunch after each change from Start modded, and keep the copy of the working setup you made before you started.