All my sitemaps created by WordPress SEO are working good but only getting problem here Sitemap: /post_tag-sitemap.xml
Unsupported file format
Your Sitemap does not appear to be in a supported format. Please ensure it meets our Sitemap guidelines and resubmit.
I did not use W3 Total Cache plugin. Than why I am getting this error ??
Please help me....
This is my website URL
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 2544929 bytes) in /home/stiffin/public_html/apnapunjab.info/wp-content/plugins/wordpress-seo/inc/class-sitemaps.php on line 468
Here is screenshot of my problem