I've gotten the error numerous times and haven't worried about it.
However, yesterday I came here and did a lengthy log post. I checked everything, re-worded a few things, was finally happy with it, hit "post"--and got the error. And my post was gone.
At my banking site (tracking interest rates) the owner put up a "if you've been helped by this site, please consider donating" and a button to donate. That worked for him for several years, then he went to very targeted, just along the side ads that were actually helpful. No flashing, nothing weird. Just ads for banks that we probably would have clicked on anyway.
I could see limited ad placement here--maybe one across the bottom--for language authors to link to their website or their book sale page on Amazon. Or tutors or programs or something. I actually think it would be a plus. OH! And ads for bookstores that sell a lot of language books would be wonderful.