After upgrade i have the same problem
Same here. The XML Sitemap became unreachable, disabled all plugins and began reactivating one by one. NextGEN Gallery v2.0.27 seems to be causing the issue. I also reported it over on the NextGEN forum.
http://wordpress.org/support/topic/nextgen-gallery-causing-xml-sitemaps-to-break?replies=1
Problem fixed after update Next Gen Gallery
Yes I confirm problem solved after last nextgen update!
Yes I fixed it the same way.
But I found the ngg_tag-sitemap.xml is dated modified 1970-01-01 00:00
Which is strang.
And when I get in I found all URLs are pointing to the same wrong page with no relation to the tag.
I just have the feeling some thing is missing and the consequence is Google doesn’t sees the images within the NGG galeries if using the thumbsnail list
Hence poor ranking even with hundreds of interesting well tagged images in NGG.
Any feedback on this?
Thanks for it
