Error-message when trying to export page/export website

I’m desperate. I get this error message when i want to export a page or the website. Exception while exporting site NSMutableRLEArray replaceObjectsInRange:withObject:length:: Out of bounds
I have an older MacBook Pro and recently upgraded to El capitan. I use an older version of Rapidweaver but never had any problems so far. Somebody has an idea of what could be the problem? I urgently need to upload changes to my website! Thanks a lot.

I too have had this problem. Am updating my site (which I’ve not done for about 3 years) and suddenly when I go tp review on a blocks page I get the same message. Any suggestions of how to fix much appreciated.