I just responded to a post, and got an error message. I was able to use the back arrow to get back to my post, then clicked the green "post" button again and this time it seemed to take it.
I took a screenshot of the error message, but then when I tried to attach it to this bug report, got another error. In case it's helpful, the error message looked like this:
An error occurred while processing your request.
Thanks for reporting this.
Could you upload the screenshot to a 3rd party like Cloudup, then share the link? Seeing how the error message appears would be helpful. 🙂