This error is part of the system, which manages the extraction of compressed archives. While "error code 11" specifically points to an inability to write data to the disk or a failure in the decompression algorithm, several underlying issues can trigger it:
If the game was downloaded via torrent, the data may be incomplete or corrupted. unarc.dll returned an error code 11 sims 4
Decompressing The Sims 4 often requires up to three times the final install size in temporary space. This error is part of the system, which
Antivirus programs frequently block the extraction of .dll and .tmp files during installation. How To Fix The 'Unarc.dll Error Code 11' On Windows unarc.dll returned an error code 11 sims 4