RSS Feed Mystery

I am new to blogs but am otherwise computer savy. My RSS Feed worked fine and I think when I upgraded manually I may have done something to make it stop working. Here is where it is located:

https://www.hamradioresources.com/blog

Now when I test the feed I get an error message that doesn’t make sense. I do not really understand how the Feed button on my blog works behind the scenes and wonder if someone would be kind enough to walk me through the process. Perhaps even try it out?

Thank you in advance!

Jon Kreski
https://www.HamRadioResources.com