The /LOWMEMORY switch forces Inno Setup to use less aggressive decompression, often bypassing RAM-related isdone.dll faults.
If you suspect the system files are actually the issue, you can re-register them via the Command Prompt: Search for , right-click it, and Run as Administrator . Type regsvr32 isdone.dll and press Enter. Type regsvr32 unarc.dll and press Enter. isdone.dll error elamigos
If the error "Unarc.dll returned an error code: -1" persists, your RAM might be unstable. Windows Memory Diagnostic tool to check for hardware errors. The /LOWMEMORY switch forces Inno Setup to use
: Security software often incorrectly flags the installer's decompression behavior as suspicious and blocks it. Type regsvr32 unarc
Enable this if you have 4GB or less. It forces the decompressor to use disk swapping instead of memory, which is slower but prevents out-of-memory crashes.