I'm having trouble with Bitcoin QT 0.11 not automatically extracting address info from my Bitcoin QT 0.7. When I try to open my Bitcoin QT wallet it comes up with an error code saying it is to unsafe to continue. How can I get hold of my info from my Bitcoin QT wallet.

  • What's the exact error message?
    – Nick ODell
    Apr 11, 2016 at 4:15
  • Runaway exception
    – kym
    Apr 23, 2016 at 5:02
  • A fatal error occurred. Bitcoin can no longer continue safely and will quit. EXCEPTION:ST13runtime_error CDB() : can't open database file blkindex.dat, error22 C:\Program files (86)\Bitcoin\bitcoin -qt.exe in runaway exception -@Nick ODell
    – kym
    Apr 23, 2016 at 5:14
  • @kym That looks like an error from 0.7, as blkindex is no longer used since 0.8. What happens if you just start the new version? Apr 24, 2016 at 8:11

2 Answers 2


A blkindex.dat error means that the block index has been corrupted or can't be opened. However, the block index is not part of the wallet, and can be deleted without removing the funds in your wallet.

With that in mind, try this:

  1. Open %APPDATA% in file explorer. Do this by pressing Windows + R, then typing %APPDATA%.
  2. Open Roaming\Bitcoin.
  3. Make a new folder in there called 'old block files,' or something similar.
  4. Move every file in that folder except wallet.dat into the old block files folder.
  5. Optionally, delete the 'old block files' folder.
  6. Start Bitcoin 0.11, and your computer will redownload the block chain. This will take a few hours.

There are two ways of upgrading from such an old version: either perform the intermediate upgrade steps (0.7 -> 0.8 -> 0.9 -> 0.10 -> 0.11) or export you wallet, clear the bitcoin directory and import the wallet again.

The first option should be pretty straight forward. The second option requires you to use the GUI to export the wallet or the individual private keys, upgrading Bitcoin QT and then importing them.

The JSON-RPC calls dumpprivkey and importprivkey can be performed for each address and will get your addresses into the new version. Be careful to keep a backup copy of the wallet.dat file before clearing the bitcoin directory.

  • can't even get into my bitcoin-qt 7 wallet to import!
    – kym
    Apr 23, 2016 at 5:15
  • No need for incremental updates. Bitcoin Core's wallet files are backward compatible down to very early versions (0.3.x at least if not older), ignoring potential BDB version compatibilities (which can be bypassed using external bdb conversion tools). Apr 24, 2016 at 8:13

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