The role "everybody" was removed in Splunk 4.0. Did you recently upgrade?
You should update your metadata files to remove the "everybody" user. In Splunk 4.0 you don't need an "everybody" named role, since you can say the same thing with a wild card. For example:
access = read : [ * ], write : [ admin ]
This means everyone can read, and only the "admin" role can write.
See the following from the docs:
In older Splunk versions we used role "Everybody". In recent builds this role is renamed as "User". Starting with 4.1.x the role "Everybody" is no longer used. As a result warning message regarding the unknown role Everybody is logged in splunkd.log
To address this message, the file passwd needs to be updated. Before making any changes, make a backup of file passwd.
On unix environment open using vi and run the following:
This should replace Everybody with role User.
On Windows open using text editor and replace Everybody with User.
After making these changes restart Splunk.
More accurately, in 4.x and up the role name is
user, note lower-case. Default role names in 3.x started with capital letters, in 4.x they do not. This does matter in several places.
I believe you are incorrect by saying that "user" replaces "Everybody". If I'm not mistaken there was a "User" and an "Everybody" in 3.x, and they meant two different things, so saying that the role was simply renamed is misleading. In splunk 4.x "user" is just a normal role (you can grant it or revoke it) and it don't think that was the case with the "Everybody" role in 3.x. (I think it would be more accurate to say that the "user" is the default role in 4.x, just like "Everybody" was in 3.x)