Any solution?
It is possible
without any external tools and its actually pretty simple, you also don't need pywallet, this is more complicated than helpful in your case. In bitcoin-core find the console (help -> debug window -> console)
enter these two commands (or only the second one if you don't have a password):
walletpassphrase "your password here" 60
dumpwallet dump.key
The "60" means unlock it for 60 seconds, this is the time you have to enter the second command. The password goes between the quotes "", if you don't have a password then you only need the second command.
If no error has occurred then you should be able to find the "dump.key" file somewhere in your home directory (don't know exactly which this is on Windows but you could either search your HDD for this file or instead of
you could use a fully qualified path like for example
to dump it to the root folder of c:\.
This works even when its not fully synchronized.
After this you can quit bitcoin-core and start Multibit. In Multibit you
* go to Tools->import private keys
* enter your Multibit password
* click import from and choose the "dump.key" file
* click "import keys"
This will import
more than hundred keys into your wallet, most of them will be change and reserve addresses of bitcoin-qt but
you need them all!Wait for Multibit to sync. After it has synched 100% check the wallet balance is correct.
Unfortunately you will lose the address labels. If you want to preserve the address labels then you could first import the "dump.key" with
wallet-key-tool and then export it from there directly as a new multibit .wallet file (which you don't need to import but can directly open in Multibit), this will keep all the address labels and mark the change and reserve addresses as "(change)" and "(reserve)". You can reuse all these reserve addresses if you want, just give them a different label and use them as receive addresses to request payments to you.
After you are done don't forget to add a strong password to your wallet (if not already done so) then
delete the dump.key (because it contains unencrypted keys and you don't want to have that laying around on your HDD), then empty the trash and then find a tool to
wipe all free space on your HDD to remove all traces of unencrypted keys from your HDD and unused sectors.
don't delete your old wallet.dat before you are sure it worked 100%, if it worked then don't use the old bitcoin-core wallet.dat anymore because this would add new change addresses, you must make a decision: either from now on use these keys
only in the new imported Multibit wallet and don't use the old wallet.dat anymore ever or leave everything as is and don't move any keys at all.
Under no circumstances use the same keys in parallel in both wallets!
