Ivan Atanasov from SiteGround here.
I checked and was not able to locate a Support Ticket or chat session where you are reporting this issue.
If you are facing problems with exporting your WordPress website data, please post a Support Ticket from your SiteGround User Area so our Support Team can help.
Also, Judging from the type of error message you provided here it is also possible that you are trying to open a successfully created and downloaded XML file on your local computer (possibly a Mac). If this is the case and you created and downloaded an XML file, I would recommend trying to import it in the desired location/host in order to check it’s validity.
]]>Also, I wrote a tutorial about migrating from self-hosted to .com here: https://cmljnelson.wordpress.com/2018/08/11/migrating-from-self-hosted-site-to-wordpress-com/ which might be useful to you.
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