Many AVs (McAfee, Norton, Bitdefender, even Windows Defender) quarantine steamclient64.dll because:
If you are using a (like for modded Skyrim VR), ensure you have the correct version of steamclient64.dll for that emulator. Re-copy the crack/emulator files.
Moving game folders manually without updating registry entries can confuse the game launcher. Step-by-Step Solutions to Fix the Error unable to load library steamclient64.dll
After restoring, restart your PC and launch Steam.
Third-party modifications, "cracks," or emulation files used to bypass Steam DRM often rely on a modified steamclient64.dll which Windows Defender easily detects and deletes. How to Fix "Unable to Load Library steamclient64.dll" Step-by-Step Solutions to Fix the Error After restoring,
Steam games rely on Visual C++ libraries to run 64-bit DLL files properly. Corrupted libraries will break the file link. Go to the official Microsoft Visual C++ download page.
This error typically appears on 64-bit versions of Windows and is most commonly associated with games launched via Steam, though it can also appear for pirated copies or games using specific emulators. The message indicates that the application cannot find or access a critical dynamic link library (DLL) file required to communicate with Steam’s client. Corrupted libraries will break the file link
The DLL error often stems from a partial update. Deleting everything but your games forces a clean, fresh installation of the Steam client without making you re-download 500GB of games.