encoding error

i can generate sitemaps fine, but when i go to the google sitemap index url it says:

This page contains the following errors:

error on line 1 at column 1: Encoding error
Below is a rendering of the page up to the first error.

what am i doing wrong please?

Hello ,

I think you are using Chrome. This is an error related to Chrome. If you check your sitemap file with any other browser you can see that it is working correctly.