Bitcoin-Qt version 0.8.6 released
9 December 2013

Bitcoin-Qt version 0.8.6 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 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.
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