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Hi Christian, I'm sorry to hear about the issue. Here's what I would do: 1. Try to use a free xml sitemap generator (Google free xml sitemap generator) and manually upload it to your server and then submit that. That may involve turning off the Yoast xml sitemap generator. You can see if you still get the error 2. Try a different plugin to generate the sitemap - I'd recommend this one: https://wordpress.org/plugins/google-sitemap-generator/ If you are still getting the same error, I would take Everett's advice and call your web host.

I would like to 2nd this proposition of a feature. Half of our agency SEO battles are documenting and communicating completed tasks for a client, to the client.

Nice happy to hear that do you work with Greg Reindel? He is a good friend I looked at your IP that is why I ask? Tom