I could not save my site. I checked RapidWeaver FAQ and found it was due to ScopedBoo running out of entries at 255, checked my ScopedBoo and Indeed, it had reached 255. Googled how to clear ScopedBoo, but no joy.
Being a Linux admin, I just entered kill -9 [pid]
[pid] means add the process ID that is found right after the words ScopedBoo on the left in terminal. This immediately kills the process and allows you to save your site. RealMac said we should reboot, but I did not want to lose my changes and did not trust auto-backup. So if you had this problem, try this and save your site first. I shall now reboot