Hello, we apologize for the inconvenience you’re experiencing with the sitemap unsupported file format error. This error typically occurs when the XML declaration is not at the start of the document.
To fix this issue, please ensure that the XML file starts with the correct header:
Make sure that the namespace in the header ends with 0.9 and that you’re using the right quotation marks to enclose XML attributes (straight single or double quotes only).
If the error persists, you can check your sitemap’s status code using the httpstatus tool. If the status code is 200, make sure to redirect all XML sitemap variations to the final variation of the XML Sitemap.
After making these changes, clear your website cache and try to submit your sitemap in the Google Search Console again. This should resolve the issue.
If you need further assistance, please feel free to ask.
Sources:
Rank Math Sitemap Issues and Their Fixes » Rank Math
How to Fix “Incorrect HTTP Header Content-Type” Error in Sitemaps » Rank Math
How to Fix “Sorry, This File Type Is Not Permitted for Security Reasons” Error » Rank Math
This is an automated reply from Rank Math Support Bot. If you need further assistance, please reply to this topic and a human support agent will reply to you shortly.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.
