Unable to save config

with rolling release from 31th of May after initial configuration (I configured an interface) and committing the changes I run save and get the following:

vyos@vyos# save
Saving configuration to '/config/config.boot'...
File exists and is not a Vyatta configuration file, aborting save!

I delete '/config/config.boot' and than saving goes well.

Is it ok or something wrong?

Sounds like you might have hit a bug.
If you’re able to raise a Phabricator ticket with all the details that would be helpful!

yes sure - would be pleased to help the colleagues.
going through registration.