Thank you very much for your reply Amy!
I have old config file but I don't want to simply replace the new one because new one contains some fresh-good data. I will try with scramble key, spider password, and api-scramble key, that is very good suggestion.
I have the option to reset passwort but I had another error message so I didn't want to bother about that..
I have only one user on the system and that is username: admin with password: admin (I am at test phase right now).
I will try your suggestions and let you know if it works out or not.