If you are getting any 404 errors on a WordPress site it’s usually caused simply because of a permalink issue. Whenever you install a new theme (especially one with custom post types) you should always first go to Settings->Permalinks and re-save your settings. This will ensure your .htaccess file gets updated correctly and avoid any 404 errors.
Fixing 404 Errors
Step 1: Go To Settings->Permalinks and click the save button
Step 2: Re-try your post/page that had the 404 error
Step 3: If it’s fixed you are done. Otherwise go back to the permalinks page and try using default permalink struture
Step 4: Try again. If it works now then it’s likely you’ll have to edit your .htaccess file manually when making your custom permalink changes or you need to verify you have no conflicts with other post, page, category, media…etc (aka something else has the same slug) You can test by deleting the page/post giving you the 404 error and seeing if it renders something else once deleted.