Windows Defender and other antivirus tools sometimes quarantine coserver.dll. That file is part of the LastCO client. If it is removed, the game will not start or will fail while patching.
Windows Security (Windows 10 / 11)
coserver.dll.If the game already failed to load, also check Protection history in Windows Security. If coserver.dll was quarantined, restore it, then add the exclusion above.
Using Norton, Avast, Bitdefender, or another scanner: open its settings, find Exclusions / Exceptions / Allowed threats, and add coserver.dll (or the LastCO folder). Then restart the launcher.
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Open the launcher from inside the LastCO folder and let it auto-patch completely.
Click Settings, set your preferences, then hit Accept.
That's it — see you in Twin City! Problems? Join our Discord for instant admin support or email [email protected].
coserver.dll (or the whole LastCO folder) from your antivirus scan, then restore the file if it was quarantined. Click for step-by-step Windows Security instructions.Create your free account now — it takes less than a minute.
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