This error message will occur when you try to save a guest pass benefit to multiple membership levels when you have more than 20 membership levels on your membership program. The benefits list Knowledgebase article instructs on how to add benefits past 20 membership levels. However, when receiving this error message, you will need to use the instructions in that Knowledgebase article to update the additional levels incrementally. Instead of updating all of your levels past the 20 membership levels that currently show at one time, you will need to update these one or two at a time to add the guest pass benefit.