Bitcoin Forum

A critical bug fix was provided in an emergency release of Bitcoin 0.8.5 earlier this evening. On September 9, Bitcoin-Qt users with versions more recent than 0.8.0 were unable to start their software and received errors that their database was corrupt:

coin database inconsistencies found

Users were then prompted to reindex the block chain, a process that could take hours and was ineffective in resolving the inconsistencies. Bitcoin-Qt is the graphical version of the standard bitcoin client and the problem was later observed in Bitcoind, the command line version.

Negative Transaction Version Numbers
The problem was caused by an abnormal transaction published in block 256818 around midnight EST on September 9. Bitcoin transactions contain fields including a version number, input parameters and output parameters among other things. The version number is currently set to 1 and allows for the network to adapt to different transaction types in the future while still providing support for older transactions.