I'd recommend uninstalling 0.3.19 first.
i used the .zip distribution of 0.3.19 and that one has no uninstall. but it is in c:/tools/bitcoin-0.3.19
so installing the new version into c:/tools/bitcoin-0.3.20 did not cause any conflicts with having both versions on the pc in the same time.
the idea is to have a bitcoin directory with a simlink to the latest version at the same place but being able to point it to a newer version when available.
my only 'negative' comment: it did not rescan the blockchain on start up (or i did not figure out how to use it)
- i've copied a different wallet into AppData/Roaming/Bitcoin folder and started the client
- it showed a high number of blocks, this i understood as the client having access to blockchain downloaded by the previous client
- the balance in client was not the same as client expected (and confirmed by blockexplorer)
could it be possible to drop last X blocks from the chain in order to save myself downloding the whole blockchain? p.ex. delete last 100 blocks and download them again. or a button to trigger rescan manually in the future?
or hint how to use the rescan feature on windows?
Thanks a lot for your work!