Ran into an interesting problem with WordPress the other week and thought I would share the various solutions to the problem where you do not have permission to preview draft posts in WordPress or end up with 404 errors on posts in WordPress that are published. One or more of these tips may resolve your issue, but remember to first and foremost disable all plugins as a first step when troubleshooting any WordPress issue. If that resolves your problem, then start activating 1 plugin at a time until you find the culprit plugin. This resolves about 90% of all WordPress issues that crop up, so make sure you do the disable all WordPress plugin method of troubleshooting first.
If you try to preview a published or scheduled article and you get a post page that says you do not have permission to preview this post then the following should be attempted.
Check WordPress Address and Site Address
The culprit which may be a bug in WordPress that leads to you do not have permission to preview drafts in my case ended up being a mismatch between the WordPress Address and the Site Address.
In my case, one of the URL’s was set to http://domain.com with the other set to http://www.domain.com and because one URL had the www and the other did not, it caused the you do not have permission to preview this post WordPress error.
Update WordPress Permalinks
This is especially an issue if you do a bulk import of WordPress blog posts or create a new WordPress blog, sometimes the permalinks can get confused and this will lead to 404 errors when viewing published WordPress blog posts or other URL oddities. All you have to do is Open your WordPress –> Settings –> Permalinks menu and then click on one of the permalink settings, click update and then select the permalink setting you had previously and click update again.
Typically you could use Post Name instead of Custom Structure for the post name, as this is now built into the later versions of WordPress and having custom structure with %postname% is a legacy configuration from older versions of WordPress.
Flush Browser Cache
Another thing you may need to do as an additional step or the only step is to flush your browser cache or try your same attempt with an Incognito or browser with a Private mode. This is different for each browser, but if you still have the issue with being unable to preview WordPress posts or getting permission issue with WordPress preview after the above attempts try flushing browser cache.
Finally, the last step if none of the above has solved your issues you can replace your WordPress install, you can do this with the automated WordPress reinstall which can be found in your WordPress –> Dashboard –> Updates
Then go ahead and click on Re-install Now
again, remember to make sure you have any caching plugins disabled and try to hit your preview button again on a blog post and you shouldn’t see the you are not authorized to preview this post error any longer on your WordPress blog.
If one of the above tips to solve your preview not authorized WordPress issue, let me know and I will see if I can find something else that helps but in doing my research as well as resolving my own issues one of these should resolve the issue, especially if you disable all WordPress plugins and try again after completing the above options to try.
Good luck WordPress users.