how to fix WordPress Admin Panel 404 Issue?

I’m using WordPress version 6.3 and I’m currently dealing with an issue of whenever I click a link in my admin panel it sends me to a 404 page not found. Whenever I delete the .htaccess and am able to get into the permalinks and flush it; it changes the index.php in the wp-admin page and causes an HTTP 500 error. I’ve tried disabling plugins, disabling themes, replacing the wp-admin and wp-includes folders with those of a fresh install, editing the wp-config, editing the .htaccess.

The issue you’re facing is quite complex, but I’ll try to provide a systematic approach to troubleshooting and hopefully resolving it:

1. Backup Everything: Before you proceed with any of the steps, ensure you have a complete backup of your WordPress site, including the database.
2. Check .htaccess File:
   • You mentioned that you’ve edited the .htaccess file. Ensure that the default WordPress .htaccess rules are present:
     # 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
   • If you have additional rules in your .htaccess file, consider commenting them out temporarily to see if they’re causing the issue.
3. Update WordPress Core:
   • Even though you’ve replaced the wp-admin and wp-includes folders, consider downloading a fresh copy of WordPress 6.3 and replacing all files except the wp-content folder and wp-config.php file.
4. Database Check:
   • Sometimes, the site URL or home URL in the database might be incorrect. Access your database using phpMyAdmin or a similar tool and check the wp_options table. Ensure that siteurl and home options have the correct URL.
   • Consider using a database repair tool. Add define('WP_ALLOW_REPAIR', true); to your wp-config.php file. Then, visit http://yourdomain.com/wp-admin/maint/repair.php and choose to repair and optimize the database.
5. Check File Permissions:
   • Incorrect file permissions can lead to HTTP 500 errors. Directories should be 755 or 750 and files should be 644 or 640.
6. Debugging:
   • Enable debugging in WordPress by adding these lines to your wp-config.php:
     define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );
     After adding these, errors will be logged to a debug.log file inside the wp-content directory, which might give more insights into the issue.
7. Server Configuration:
   • If you have access to the server configuration, check the server error logs. This might provide more detailed information about the HTTP 500 error.
   • Ensure that the server is running a compatible version of PHP for WordPress 6.3.
8. Contact Hosting Provider:
   • Sometimes, the issue might be server-specific. Contacting your hosting provider might provide insights, especially if there are server-level configurations or restrictions causing the issue.
9. Consider a Staging Site:
   • If all else fails, consider setting up a staging site. Migrate your site to the staging environment and see if the issue persists. This will help determine if it’s a server-specific issue.

Remember, troubleshooting can be a process of elimination. It might take some time, but systematically going through these steps should help narrow down and hopefully resolve the issue.