Hello,
What version of JoomFish do you use? If you're using the latest 2.1.5 version, there is unfortunately a bug in it causing this error. I've already reported it to the JoomFish's developers, so hopefully they'll fix it soon. In the meantime, I'd suggest to reinstall JoomFish and use the older 2.0.4 version.
If you are using JoomSEF version 3.7.4 or newer, you can also use the Purge URLs button instead of Update - it will move all the SEF URLs to Trash, and they will be updated automatically next time the website is browsed. You won't lose any of your custom meta tags using this option.
Best regards,
ARTIO Support Team