wp_admin is redirecting to itself

I’ve been having a host of problems on the admin side of things. The public side of things is running fine.

Issue 1: Several of the admin page links route to 404, but not all.

Issue 2: after clearing caches and such, now the /wp_admin redirects to itself with endless 302 codes.

I’m really at a loss about what’s happening. I have several plugins that should be updated, but the update page is one of the ones that gives a 404.

This might help recognize the problem. Here are some samples.

These admin urls are fine:
* /wp_admin/nav-menus.php
* /wp_admin/edit.php?post_type=page
* /wp_admin/tools.php
* /wp_admin/themes.php
* /wp_admin/widgets.php
* /wp-admin/admin.php?page=revslider

These give 404:
* /wp_admin/plugins.php
* /wp-admin/options-general.php
* /wp-admin/admin.php?page=gadash_settings

This goes into a redirect loop with 302:
* /wp_admin

This gives a 301, which directs to ‘/wp_admin’ which has the 302 loop:
* /wp_admin/index.php

Any thoughts or ideas would sure help.

Steve