Create a new folder directly in your root drive (e.g., C:\Games or C:\Installer ).
The Unarc.dll error code 12 can occur due to various reasons, including:
Disable Antivirus and Windows DefenderThe most common culprit is your security software. Antivirus programs often flag the decompression of large archives as "suspicious behavior." Open Windows Security. Go to Virus & threat protection > Manage settings. Turn off Real-time protection temporarily.
Important: Do not blindly download unarc.dll from unknown, free DLL sites, as these are often malware carriers. Follow these steps to fix the root cause instead. 1. Fix Missing/Corrupted System Libraries (VC Redist)
Note: If you use a third-party antivirus (like Avast, Malwarebytes, or McAfee), right-click its icon in the system tray and select until the next system restart. Retry the installation. 2. Verify and Re-register Unarc.dll and Isdone.dll
A: No, the installation will not finish, and the files will be corrupted.
The error often reads:
After it installs, open msconfig again, uncheck , and restart normally. 3. Check and expand your Virtual Memory (Paging File)
For 64-bit Windows running 32-bit installers:
Open Command Prompt as Administrator and type: regsvr32 unarc.dll to register the new file. 4. Limit CPU Cores via Task Manager
If you use a third-party antivirus (like Avast, Malwarebytes, or Bitdefender), right-click its icon in your taskbar tray and pause protection. Re-run the installer as an administrator.
If you are trying to install a large game—particularly a "repack" version—on a Windows 64-bit system, you might encounter a frustrating interruption. A popup appears, halting the installation and displaying:
Error code 12 is frequently triggered by unstable or failing RAM modules. Bad memory sectors alter data bits during heavy extraction tasks. Press Windows Key + R , type mdsched.exe , and hit . Click Restart now and check for problems . The PC will reboot into a diagnostic screen.
Ensure the installation drive has at least 1.5x the space of the final game size. Furthermore, use the Command Prompt to check for disk errors: Open CMD as Administrator.
Use: C:\Games\Setup.exe