I used to receive RSS feed on a set of tags, such as https://stackoverflow.com/feeds/tag?tagnames=java+or+spring&sort=newest, but today it started to produce 404, though feed link at https://stackoverflow.com/questions/tagged/java+or+spring still points to that address.
Feeds on individual tags ( https://stackoverflow.com/feeds/tag?tagnames=java&sort=newest) and on intersection of tags ( https://stackoverflow.com/feeds/tag?tagnames=java+spring&sort=newest) are working correctly.