If you view a Discourse instance with the Googlebot Useragent so that Discourse prints the instance without JS at the top of a topic it gives a link back to the category in the format http://example.com/category/category_name
This link then redirects to back to the shorter version, http://example.com/c/category_name
The issue is if the above category is a subcategory, that second link is a 404, it should be linking to the correct location, ie http://example.com/c/parent_category/category_name
This issue doesn’t appear when you have JS enabled/aren’t the Googlebot.
Happy to give and info if wanted! You CAN repeat this on https://meta.discourse.org by using this post for example and CURLing the URL it gives back to the category listing.
macbook-air:~ $ curl -IL https://meta.discourse.org/category/wordpress
HTTP/1.1 302 Found
Server: nginx
Date: Tue, 06 Jan 2015 23:46:22 GMT
Content-Type: text/html; charset=utf-8
Status: 302 Found
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
Location: https://meta.discourse.org/c/wordpress
Set-Cookie: destination_url=https%3A%2F%2Fmeta.discourse.org%2Fcategory%2Fwordpress; path=/; Secure
Set-Cookie: _forum_session=BAh7BkkiD3Nlc3Npb25faWQGOgZFVEkiJTZmNWI0ZDRmN2VjMjgwYjcxZDUwYWU1YzBmM2YwOTMwBjsAVA%3D%3D--eec8fe7c8eff16a59a7b780f2f23311498727b2b; path=/; HttpOnly; Secure
X-Request-Id: 4ab71e35-9a4f-4bdf-a9f9-b345f42dfb0a
X-Runtime: 0.019158
X-UA-Compatible: IE=edge
Strict-Transport-Security: max-age=31415926
HTTP/1.1 404 Not Found
Server: nginx
Date: Tue, 06 Jan 2015 23:46:22 GMT
Content-Type: text/html; charset=utf-8
Vary: Accept-Encoding
Status: 404 Not Found
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
Set-Cookie: destination_url=https%3A%2F%2Fmeta.discourse.org%2Fc%2Fwordpress; path=/; Secure
Set-Cookie: _forum_session=BAh7BkkiD3Nlc3Npb25faWQGOgZFVEkiJThhZTRiNmI3ZTkyNDVmMmE5MjYxNzE1OWNlZmJiNzQyBjsAVA%3D%3D--8c98906a8920b80c989a0cf916802b677fea4ed6; path=/; HttpOnly; Secure
X-Request-Id: 4869fed5-535c-4253-a440-4c4f72da1147
X-Runtime: 0.090909
Strict-Transport-Security: max-age=31415926
macbook-air:~ $
