Unable to Validate Card


On wordpress site kellermandesign.com, with Yoast SEO Plugin installed, I follow the instructions and enter the username and flip the switch to activate the meta tags, and the html is indeed updated with the meta tags.

But when entering the URL in the Card Validator I get “Unable to render Card preview” and the log says “ERROR: Internal server error”.

I found a previous topic with the same errors, suggesting changes to .htaccess and robots.txt were the culprit. But I haven’t made any changes to .htaccess (and the file only contains basic wordpress info) and I haven’t created any robots.txt file.

So I’m at a loss. From any and all info I’ve come across, I’ve done everything I’m supposed to do, and the code is there on the page, but still I’m getting nowhere with the validation.

Any help would be much appreciated.