Samuel Aguilera

There are three possible scenarios where this plugin does something. In all cases, the attachment page must exists, the plugin will not run for deleted attachments:
A) A visitor lands on an attachment page and the parent post is available (not in trash or deleted). A 301 redirect will be issued to redirect the visitor to the parent post.
B) A visitor lands on an attachment page and the parent post was already deleted from trash. A 302 redirect is issued to home page (this can be changed to 301 if you want, see FAQ for more details).
C) A visitor lands on an attachment page and the parent post is in trash, therefore not available for the visitor. It returns a 404 error code to prevent endless redirection loop in old WP releases and redirecting to trashed/not available posts.
There is no options page, simply activate it and will do the job.
If you’re happy with the plugin <a href="https://wordpress.org/support/plugin/attachment-pages-redirect/reviews/?filter=5" rel="ugc">please don’t forget to give it a good rating</a>, it will motivate me to keep sharing and improving this plugin (and others).
<h4>Requirements</h4>
<ul>
<li>WordPress 4.8 or higher.</li>
</ul>

Attachment Pages Redirect

Redirect attachment pages or return a 404 error for them based on the parent post status.

MembershipWorks

Lightweight and clean Redirect plugin performs HTTP redirection, and supports matching of GET query parameters without regular expressions (for those pesky ?page=123 or ?escaped_fragment=xxx urls).
<ul>
<li>No advertising, links or tracking code.</li>
<li>Lightweight code (~100 LOC).</li>
<li>301, 302 or 307 HTTP redirect.</li>
<li>Specify from and destination urls in a list manually.</li>
<li>Does not require creating a custom page.</li>
<li>Match url regardless of GET parameters.</li>
<li>Match url only if no GET parameter exists.</li>
<li>Match url only if GET parameter exists (value does not matter).</li>
<li>Match url only if GET parameter exists and value matches.</li>
<li>Does not support Multisite (sorry!).</li>
</ul>
A free plugin from the workshop of <a href="https://membershipworks.com" rel="nofollow ugc">MembershipWorks</a>. Serbian translation thanks to Ogi Djuraskovic <a href="http://firstsiteguide.com/" rel="nofollow ugc">firstsiteguide.com</a>.

Redirect List

A really lightweight, clean and simple 301, 302 or 307 HTTP redirect plugin that also supports matching of GET query parameters.

Attachment Pages Redirect vs Redirect List