Did you check for the things asked in the first error message?
That the wallet is unlocked and that it can write to the chosen location?
I haven’t seen the second one before. So you got the second error first, and then afterwards the first error? Both with the original blockmarket installation, which still shows your balance correctly?
And after you installed the lastest version of blockmarket, it’s using the same “SyscoinCore” data directory with the same content, but it’s not asking you for a password when trying to dump the private keys?