Commun error message with Unarc.dll "An error occurred while unpacking: archive corrupted! Unarc.dll returned an error code: - 7" "Archieve header is corrupt" Below is the explaination of the Unarc.dll error code: unarc.dll returned an error code -6 => file read operation failed unarc.dll returned an error code -7 => Archive data corrupted (decompression fails) unarc.dll returned an error code -12=> CRC check failed unarc.dll returned an error code -14=> Corrupted archive. SOLUTION: unarc.dll is often use by installers to decompress there files. This dll file is used by the software / game in order to decompress there files during the installation process in Windows based PC.If you got an error message during the installation of a software involving this dll, make sure: That you have at least 2 time the size of the requirement size as free space on the operating system drive. The installation folder should meet the system requirement size. If the situation above is already met, and you still have the issue, try the following: Turn off your antivirus. Install or re-install your software. Once it's done, you can trun your antivirus program back on.