---
title: Bitcoin-Qt version 0.5.3 released
---
Bitcoin-Qt version 0.5.3 is now available for download at:
<http://sourceforge.net/projects/bitcoin/files/Bitcoin/bitcoin-0.5.3/>

This is a bugfix-only release based on 0.5.1.
It also includes a few protocol updates.

Please report bugs using the issue tracker at GitHub:
<https://github.com/bitcoin/bitcoin/issues>

PROTOCOL UPDATES
----------------

* BIP 30: Introduce a new network rule: "a block is not valid if it contains
a transaction whose hash already exists in the block chain, unless all that
transaction's outputs were already spent before said block" beginning on
March 15, 2012, 00:00 UTC.

* On testnet, allow mining of min-difficulty blocks if 20 minutes have gone
by without mining a regular-difficulty block. This is to make testing
Bitcoin easier, and will not affect normal mode.

BUG FIXES
---------

* Limit the number of orphan transactions stored in memory, to prevent a
potential denial-of-service attack by flooding orphan transactions. Also
never store invalid transactions at all.

* Fix possible buffer overflow on systems with very long application data
paths. This is not exploitable.

* Resolved multiple bugs preventing long-term unlocking of encrypted wallets
(issue #922).

* Only send local IP in "version" messages if it is globally routable (ie,
not private), and try to get such an IP from UPnP if applicable.

* Reannounce UPnP port forwards every 20 minutes, to workaround routers
expiring old entries, and allow the -upnp option to override any stored
setting.

* Skip splash screen when -min is used, and fix Minimize to Tray function.

* Do not blank "label" in Bitcoin-Qt "Send" tab, if the user has already
entered something.

* Correct various labels and messages.

* Various memory leaks and potential null pointer deferences have been
fixed.

* Handle invalid Bitcoin URIs using "bitcoin://" instead of "bitcoin:".

* Several shutdown issues have been fixed.

* Revert to "global progress indication", as starting from zero every time
was considered too confusing for many users.

* Check that keys stored in the wallet are valid at startup, and if not,
report corruption.

* Enable accessible widgets on Windows, so that people with screen readers
such as NVDA can make sense of it.

* Various build fixes.

* If no password is specified to bitcoind, recommend a secure password.

* Automatically focus and scroll to new "Send coins" entries in Bitcoin-Qt.

* Show a message box for --help on Windows, for Bitcoin-Qt.

* Add missing "About Qt" menu option to show built-in Qt About dialog.

* Don't show "-daemon" as an option for Bitcoin-Qt, since it isn't
available.

* Update hard-coded fallback seed nodes, choosing recent ones with long
uptime and versions at least 0.4.0.

* Add checkpoint at block 168,000.
