Update error always showing

Hello,

Everytime I check for updates, I get the following error message:

Should I bother to get this fixed, because I have the impression that everything is updated?

thanks,
René

Usually, when a repository fails to deliver, it is because the Internet connection is down at the user end, In which case all of that user’s repositories will report an error. Or, it is because a specific repository is down at its end. This is most likely to happen to a repository that has added by a user. It is rare for one of the official, pre-installed Ubuntu repositories to go down. Though, it does happen rarely and temporarily.

Extras is not active for Vivid at this time but you could check back by going here. Did you upgrade 14.10 to 15.04? For spotify I’d verify what PPA to use, if you want that software.