Water
ISDone.dll or unarc.dll error
“ISDone.dll: An error occurred when unpacking! Unarc.dll returned an error code: -1” comes from a game installer that unpacks a heavily compressed archive, and it means the unpack failed. The drive filled up, the PC ran out of memory, a downloaded file is damaged, or something blocked a file as it was written.
Updated 29 October 2026 · Em português
What the error code means
- -1
- An error the unpacker didn’t name. Go through every step below.
- -5
- Not enough memory for the unpack.
- -6
- A file couldn’t be read: it’s damaged or missing, or the drive has errors.
- -7
- The data can’t be unpacked: a file of the download is damaged or incomplete.
- -11
- A file couldn’t be written: the drive is full, or something blocked the write.
These are the codes of FreeArc, the archiver unarc.dll comes from. Other numbers are rarer; start with the same steps.
How to fix it
- Make room. Free more space than the game will take once installed, on the drive you install to, and some on C: as well, where installers keep their temporary files.
- Give it memory. Close other programs, and let Windows size the page file: Settings › System › About › Advanced system settings › Performance Settings › Advanced › Virtual memory › Change, then tick “Automatically manage paging file size for all drives”.
- Check the download. A BitTorrent client can recheck every piece against the torrent and download again what’s damaged. Anything else, download again.
- Use a short folder. Install to something like
C:\Games: some installers fail on long paths, or on folder names with accents or non-Latin letters. - See what your antivirus removed. Windows Security › Virus & threat protection › Protection history lists files it blocked during the install.
- Still failing at the same point? Faulty memory corrupts an unpack too: Windows Memory Diagnostic, in the Start menu, tests it.
Why it happens
These installers pack a game into archives far smaller than the game, so unpacking needs a lot of memory and disk space for a while, and a single damaged byte stops it. That’s why the error often comes late, after minutes of progress.
Or let Water do it
Water downloads over BitTorrent, which checks every piece of a game against the torrent as it arrives, so a damaged file is fetched again before anything installs. Some of these installers Water unpacks itself; the others it runs on a desktop of its own and answers for you. You press Install, then Play.
