EB - cannot publish post, redirected to front-end 404

All of a sudden I cannot edit a post and publish it. When i click publish or update post from the backend editor, i am directed to my frontend 404 error page.

This happened all of a sudden because i was able to create a post and edit/publish it several times. Then all of a sudden i cannot edit it and i don't know what changed. ....other than too many image in the blog post???

Im running the most recent version of EB and right now i'm updating to joomla 3.7 to see if that corrects the issue??