VeeshanVault

The most common cause of 99.9% problems is bad NAT routers. This is characterized by repeated hash fails of the same piece over and over again in Azureus, due to the NAT router consistently mangling a specific piece-data packet.

Some routers employ a routing trick called Game Mode, where they rewrite the internal and external IP address bytes found within the payload of incoming and outgoing packets. This allows older games, which hard-code IP addresses within their messaging format, to function from behind a NAT setup. However, when such an address byte sequence is mistakenly found and mangled for incoming BT piece data messages, this changes the actual received piece data contents, causing them to fail later hash checking. Any incoming packet that just happens to match the address byte sequence is susceptible to mangling, which is estimated to randomly happen about once every 4GB of data.

There are three ways of fixing the problem:

1) Do not run your router in DMZ mode (where packets not explicitly forwarded are routed by default to a single machine), as many routers seem to employ game mode-like mangling by default for DMZ-bound traffic. Instead, you should enable explicit port-forwarding on your router for Azureus incoming ports.

2) If your router has such a Game mode option (many do not, even though they mangle anyway), turn it off.

3) If you have done the above two, then try connecting directly to the internet (i.e. bypass your NAT router entirely) to finish off the last piece.

Otherwise:

Check what the remaining 0.01% is. Open up the torrent details and go to the Files tab and see what files are incomplete.

If the file is Thumbs.db, desktop.ini, or .DS_Store, right click (or ctrl click) the file to bring up the context menu and choose Set Priority -> Do not download. Operating systems sometimes will generate these files automatically when you browse the directory. Because they are hidden system files they are protected and can't be replaced with the 'correct' versions Azureus downloads, so it will discard it and download again.

There was a counting error in versions prior to v2.1.0.3, this may have been causing torrents to hang at 99.x% complete. A fix was included in CVS version 2.1.0.3 build 3 (06/23/04). See LatestDailySnapshot for information on upgrading to a CVS version.

Certain D-Link routers have a known bug (specifically models DI-624, DI-624+ and DI-604) that can cause a torrent download to get stuck at 99.x% if your computer is set as DMZ. This is not limited to the Azureus client, and may not be limited to the bittorrent network. It will keep downloading the same piece over and over and the hash will fail each time it completes, which will accumulate to a lot of wasted bandwidth over time. To fix this, either disable DMZ for the remainder of the download, or disable DMZ and set up port forwarding under the "Virtual Server" section in the Advanced tab of your router's web interface for the Azureus ports.