This can be a common problem if your using WordPress
The Problem:
This is one of the most common errors WordPress users face, largely because it means that something went south with your server and WordPress doesn’t know exactly what it is.
You can easily detect this problem when you get an “Internal Server Error” or “500 Internal Server Error” when you log on to your WordPress site.The
Solution:
As you can imagine, there are a number of ways you can go about fixing this error.
Check your .htaccess file
The .htaccess file is your friend. It helps your site know how to function by directing it with rewrite rules. But it can also be a huge pain as it makes changes whenever you add new functions to your site. As such, it can get corrupted and cause you to get the dreaded error.
Luckily, there’s a quick fix.
Go to your FTP client and locate the .htaccess file in your root directory. If you can’t see it, you’d want to enable “force show hidden files”.
Once you’ve located the file, rename its file name into .htaccess_old. Reload your site.
If that fixes the error, go re-save your permalink structure (in Settings > Permalinks) to generate a new .htaccess file.
Increase your PHP memory limitI
SEs (Internal Server Errors) can also be due to insufficient memory in your wp-config.php file. In this case, the easy fix is to increase the PHP memory.
To do this, access your wp-config.php file and add the following line:
define('WP_MEMORY_LIMIT', '64M').
This strip of code will tell WordPress to increase your site’s memory limit to 64MB. Other variations of this code are set to 128MB and 256MB if your situation and hosting provider permits. You should also paste the code just before the line that says “That’s all, stop editing! Happy blogging.”
It’s worth noting that not all web hosts allow its users to increase their sites’ memory limit on their own, in which case you’ll need to ask them to do it for you.
Remotely deactivate all plugins
Sometimes a bad plugin can trigger an Internal Server Error. This happens when plugins are incompatible with your current WordPress version or when plugins are corrupted and vulnerable in the first place.
Don’t panic. You can easily fix this.
What you need to do is to deactivate your plugins and reactivate them one by one until you spot which one causes the error.
ISEs will sometimes lock you out of the wp-admin, in which you’ll have to do this remotely. Go to your FTP client, locate the wp-content folder, and rename your plugin folder into “plugins_old”.
This will deactivate all your plugins and get rid of the error, giving you access to the backend of your site. There, simply reactivate plugins individually and see which one(s) are causing the problem.
Reach out to your hostIf you’ve exhausted all the options above, it’s time to contact your web host and ask them to do it for you from their end. Most web hosts will be happy to do it for you.