In XML, all such tags should be closed by using a forward slash. So to avoid this error you need to make sure that the entered metatags in the new blogger templates is ended with a forward slash.
< meta content='index,follow' name='robots' / >(without spaces)- Meta tag which used for allowing bots to index the blog.
</head> - Closing tag for the head of the document.< / body >(without spaces) - Closing tag for the main body of the document.
HTML is mark up language and it has some flexibility when adding HTML codes. But in XHTML the case of the HTML tag does matter because if you use "< HTML >"(without spaces) tag, you should close this tag using "< / HTML >" (without spaces). You cannot enter "< / html >"(without spaces). If you do like that you will get an error message like this, "Your template could not be parsed as it is not well-formed. Please make sure all XML elements are closed properly. XML error message: The element type "HTML" must be terminated by the matching end-tag". This also apply for "BODY"tag and "HEAD" tag.
When using empty tags you should close them by putting a space before the forward slash. For example : <br> tag which inserts a line break. This is an empty tag, so to close it you should use <br /> tag. You may need to examine each code which need to be closed by forward slash. To do so you can use my post about how to fix and know html errors in blogger templates, in order to find the exact error and correct it easily.