<p>Found out a way to fix the problem - really easy too:</p>

<p>1) Copy bitcoin data files to external hard drive
2) Uninstall Bitcoin application
3) Copy bitcoin data files back to their original location
4) Download and reinstall Bitcoin application.  It finds the old files and everything works perfectly.</p>

<p>Thank you all for your help.
D</p>

CC BY-SA 3.0
2013-09-01T14:15:38.013Z
2013-09-01T14:15:38.013Z
user6542
<p>The only thing you need keep between installations of bitcoin is the wallet.dat file, which contains the keys required to spend your coins. If you are reinstalling bitcoin you can use bootstrap.dat in versions after 0.7.1 (at the time of writing the current stable version is 0.8.6).</p>

<p>Here's how to use bootstrap.dat to avoid the painfully long block chain download for a new installation: <a href="https://bitcointalk.org/index.php?topic=145386.0" rel="nofollow">https://bitcointalk.org/index.php?topic=145386.0</a></p>

<p>Even if you've already downloaded some blocks, bitcoin will check for bootstrap.dat and sync. At the time of writing the file is 13+ gb, but you can delete it once that your client has verified all the blocks.</p>

CC BY-SA 3.0
2014-01-29T16:57:42.343Z
2014-01-29T16:57:42.343Z
Mark
<h2>When I try to load my Bitcoin Wallet I get an "Assertion Failed!" window:  here is what the window says:</h2>

<p>Program: C:\Program Files\Bitcoin\bitcoin-qt.exe
File: src/main.cpp
Line: 1761</p>

<p>Expression: pfork !=NULL</p>

<p>For information on how your program can cause an assertion failure, see the visual C++ documentation on asserts</p>

<p>(Press Retry to debug the application - JIT must be enabled)</p>

<h2>(three buttons:)     Abort     Retry    Ignore</h2>

<p>I am a novice and don't know where to start.  I do have a backup on a flash-drive if that is of any help.</p>

<p>Many, many thanks for any help you can give.
Sincerely
Douglas (Scotland, UK)</p>

CC BY-SA 3.0
2013-08-28T20:48:54.857Z
Which version of Bitcoin-Qt?
Pieter Wuille
CC BY-SA 3.0
2013-08-29T15:10:31.690Z
Version: bitcoin-0.8.3-win32   - Windows XP.  By the way, it loads quite happily under another username on the same computer.  By the way, I have uninstalled and reinstalled to no effect. Many thanks for your help
user6542
CC BY-SA 3.0
2013-08-29T19:54:53.917Z
Did you initially install it under the user account where it works or where it does not work?  You may have to reference a data directory when you open it, see http://bitcoin.stackexchange.com/questions/6015/how-to-make-bitcoin-qt-client-portable-windows
Neil Neyman
CC BY-SA 3.0
2013-08-30T14:16:53.670Z
bitcoin-qt bugs are best reported on their issuer tracker at https://github.com/bitcoin/bitcoin/issues
dchapes
<bitcoin-core>
"Assertion Failed!" when I try to open Bitcoin Wallet
user6542
# "Assertion Failed!" when I try to open Bitcoin Wallet

(Asked by: username_0 on 2013-08-28)

## When I try to load my Bitcoin Wallet I get an "Assertion Failed!" window: here is what the window says:

Program: C:\Program Files\Bitcoin\bitcoin-qt.exe
File: src/main.cpp
Line: 1761

Expression: pfork !=NULL

For information on how your program can cause an assertion failure, see the visual C++ documentation on asserts

(Press Retry to debug the application - JIT must be enabled)

## (three buttons:) Abort Retry Ignore

I am a novice and don't know where to start. I do have a backup on a flash-drive if that is of any help.

Many, many thanks for any help you can give.
Sincerely
Douglas (Scotland, UK)

**Tags:** bitcoin-core

> **Comments:**
> **username_1**: Which version of Bitcoin-Qt?  
> **username_0**: Version: bitcoin-0.8.3-win32   - Windows XP.  By the way, it loads quite happily under another username on the same computer.  By the way, I have uninstalled and reinstalled to no effect. Many thanks for your help  
> **username_2**: Did you initially install it under the user account where it works or where it does not work?  You may have to reference a data directory when you open it, see http://bitcoin.stackexchange.com/questions/6015/how-to-make-bitcoin-qt-client-portable-windows  
> **username_3**: bitcoin-qt bugs are best reported on their issuer tracker at https://github.com/bitcoin/bitcoin/issues  

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## 2 answers

### Answer by username_0 on 2013-09-01. Score: 2

Found out a way to fix the problem - really easy too:

1) Copy bitcoin data files to external hard drive
2) Uninstall Bitcoin application
3) Copy bitcoin data files back to their original location
4) Download and reinstall Bitcoin application. It finds the old files and everything works perfectly.

Thank you all for your help.
D


---

### Answer by username_4 on 2014-01-29. Score: 1

The only thing you need keep between installations of bitcoin is the wallet.dat file, which contains the keys required to spend your coins. If you are reinstalling bitcoin you can use bootstrap.dat in versions after 0.7.1 (at the time of writing the current stable version is 0.8.6).

Here's how to use bootstrap.dat to avoid the painfully long block chain download for a new installation: <https://bitcointalk.org/index.php?topic=145386.0>

Even if you've already downloaded some blocks, bitcoin will check for bootstrap.dat and sync. At the time of writing the file is 13+ gb, but you can delete it once that your client has verified all the blocks.


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