Justin Tadlock 6 years ago A 404 error is generated by WordPress before templates are handled. I pretty much want to say that it’s outright impossible for your template structure to do anything like this, but I hate to rule out anything completely. I just can’t think of a possible reason this would have anything to do with templates. I’m also assuming you’re not doing anything crazy like putting CPTs into your theme. I could see a theme update being a cause for this if that were the case. Going to the “Settings > Permalinks” page (don’t have to save) flushes the rewrite rules for WordPress. There are factors that come into play on occasion where people simply need to flush their rewrite rules to straighten things out. I also use this structure with many themes (including the one on this site). No issues with CPTs and 404s. Can you link to a theme where you’re having problems? I’ve got plenty of CPTs set up on my install and can at least test this.