Error:could not complete this operation because an assertion has failed

I get the error message of "could not complete this operation because an assertion has failed" when I try to save something through Save For Web.

Try deleting your Save For Web prefs by holding ctrl-alt when you go to SFW, Failing that, do a search for "assertion failed". There have been several of these threads recently.

Thanks! It works now.

Thanks, Mick, I had the same problem this morning and deleting the prefs worked.

Thanks so much! This one had me stymied and my productivity had ground to a halt. I joined this user forum specifically in hopes of finding a solution. Thanks to your informed suggestion, I'm back in gear!

Nice to see that this helped a few people. Perhaps there should be something on this in the FAQ as it seems to be a relatively common problem.