Can’t access admin dashboard with wp-admin without /index.php after it

After I log in, I’m redirected to example.com/wp-admin/, which has a “ERR_TOO_MANY_REDIRECTS” message. If I type in example.com/wp-admin/index.php, everything works just fine. My wp-config.php looks fine. This is not a multisite setup.

My .htaccess has the following:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

Disabling all plugins, changing theme, and hard code siteurl and home values in config.php did not solve the issue.

Any ideas how to fix this?

It sounds like Apache’s DirectoryIndex may be set “incorrectly”. Try resetting this at the top of your .htaccess file:

DirectoryIndex index.php