I'd suspect the venue having the sale is probably one made by a player that hasn't been named properly. Or maybe if it's not player made the lot may have lost its name. If you go into edit town and click on lots that could be having sales, you might find one or more without any text in the name. I can't go into my game now to give you an exact description on what to do.
You'll probably find there is actually a name in the message and it is just a space because when the game tried to read the name of the venue having the sale it found nothing to report. But going into Edit Town and clicking on the venues in town you will see the dialog come up that lets you share or save or rename it. You need to check the names are all there, and provide names for any that are blank.
