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Bitcoin-Qt 0.8.6

Bitcoin-Qt version 0.8.6 final is now available from:

This is a maintenance release to fix a critical bug; we urge all users to upgrade.

Please report bugs using the issue tracker at github:

How to Upgrade

If you already downloaded 0.8.6rc1 you do not need to re-download. This release is exactly the same.

If you are running an older version, shut it down. Wait until it has completely shut down (which might take a few minutes for older versions), then run the installer (on Windows) or just copy over /Applications/Bitcoin-Qt (on Mac) or bitcoind/bitcoin-qt (on Linux).

If you are upgrading from version 0.7.2 or earlier, the first time you run 0.8.6 your blockchain files will be re-indexed, which will take anywhere from 30 minutes to several hours, depending on the speed of your machine.

0.8.6 Release notes

  • Default block size increase for miners. (see

  • Remove the all-outputs-must-be-greater-than-CENT-to-qualify-as-free rule for relaying (see

  • Lower maximum size for free transaction creation (see

  • OSX block chain database corruption fixes

    • Update leveldb to 1.13
    • Use fcntl with F_FULLSYNC instead of fsync on OSX
    • Use native Darwin memory barriers
    • Replace use of mmap in leveldb for improved reliability (only on OSX)
  • Fix nodes forwarding transactions with empty vins and getting banned

  • Network code performance and robustness improvements

  • Additional debug.log logging for diagnosis of network problems, log timestamps by default

  • Fix Bitcoin-Qt startup crash when clicking dock icon on OSX

  • Fix memory leaks in CKey::SetCompactSignature() and Key::SignCompact()

  • Fix rare GUI crash on send

  • Various small GUI, documentation and build fixes


  • There have been frequent reports of users running out of virtual memory on 32-bit systems during the initial sync. Hence it is recommended to use a 64-bit executable if possible. A 64-bit executable for Windows is planned for 0.9.

Note: Gavin Andresen's GPG signing key for SHA256SUMS.asc has been changed from key id 1FC730C1 to sub key 7BF6E212 (see