We've seen this problem mentioned quite a few times.

I kept thinking people were getting errors and just weren't describing them. Here's what I'm now convinced was happening.

You'd upload the new logo, and it would look like it just refreshed the page. To save on overhead, Chrome/Chromium would keep displaying the cached old image. I personally knew to hard refresh the page with a Ctrl+F5, but it looks like our users don't already know that.

So, how do we force an image to be not cached, or at least re-polled every time?

We can prevent caching by setting headers on the image every time. But that's bulky and cumbersome. Instead, we can just throw a ? and a random string at the end, and the browser thinks its a different image every time.