Hey. I have the same problem. I'm trying to restore a wallet backed up in version 0.4.24, but I get the same error. I am dead sure of the password, which does have special characters (nothing outside of what you can type on your standard english keyboard though. no spaces). I checked and the master key record type structure is correct. Using 0.4.24 doesn't work either, it still gives me the same error.... same with 0.5.3
If the password won't even work on the old versions, it sounds like either your password really is wrong or there is a separate issue from what everyone else in this thread is experiencing.
In any case, I will think about if we can maybe add an option to force the backup to restore even if it thinks the password is wrong.
I'm totally locked out. Tried so many of the versions and all I get is invalid/wrong password. BTW I prefer the 5.0/5.3 splash screens. I don't know for sure but it looks like a malicious individual is the culprit for my password being wrong. Nobody I know personally knew my password, or even what bitshares is, but I found this website video.b1.org up to something. Is there anything I can do?