Try going to Settings > Permalinks in the WordPress admin and then clicking “Save Changes” at the bottom. You don’t need to actually change anything, just re-save. This will rebuild the permalink structure and fixes 90% of these issues.
The next thing to check is to make sure you haven’t changed the panorama slug to one already in use by a post, page, category or tag.
If that doesn’t work, it’s likely there is a plugin or theme that’s causing the issue. Please follow the steps here to identify which plugin or theme is causing the issue.