With reference to: Bookmarks have evolved into Saves
Double-clicking on the new Saves icon (below the Downvote arrow) displays the An error occurred message approximately 10-20 percent of the time (presumably depends on factors such as double-click speed, quality of internet connection, mouse movement, etc.)
It is reproducible. However, to display the error message it may be necessary to double-click quickly multiple times in a row.
I tested this on Stack Overflow and Meta Stack Exchange
I expected a "Saves Manager Dialog" to appear when I double-clicked the Saves icon, however this has not been implemented.