This article will help you to understand how to fix 500 Internal Server Error.
Some website expert said, the two most common causes of this error are exceeding your server’s PHP memory limit and a corrupted .htaccess file. The .htaccess file in your WordPress directory can become corrupted after you install a plugin or make another change to your WordPress site. The fix is simple. All you need to do is create a new .htaccess file and increasing a site’s PHP memory limit .
Creating a New .htaccess File
Open your WordPress root directory in FileZilla or your preferred FTP client. This is typically called public_html. If you see folders named wp-admin and wp-content, you’re in the right place. If you don’t see your .htaccess file or any dotfiles, make hidden files viewable by clicking Server and selecting Force Showing Hidden Files.
Once you find your .htaccess file, right-click it, and rename it “.htaccess.bak”. This essentially deletes your site’s .htaccess file, so we need to create a new one. Go into your WordPress admin area. Hover over Settings, and select Permalinks. Scroll down to the bottom of the page, and click Save Changes.
Open your website in your browser. If the 500 internal server error is gone, it was caused by a corrupted .htaccess file and your issue is now fixed. You’re still seeing the error, you have some more tests to run.
Increasing Your PHP Memory Limit in WordPress
PHP memory limits are set by your host and WordPress. WordPress will attempt to increase your limit if you begin exceeding it, but it can only go as high as the limit your host has placed on your server. This limit is often lower for shared hosting plans. You need to increase your PHP memory limit in WordPress and refresh your site to test whether or not this is causing your 500 internal server error.
Open your root directory, and locate your wp-config.php file. Right-click on the file, and select Download to download it to your computer. Open the file in your preferred text editor, and add this bit of code under the opening PHP tag:
Save the file, and re-upload it to your root directory, overwriting the original file. Refresh the client, and refresh your site. If you still see the error, you are not having PHP memory limit issues. Remove the above code from the wp-config.php file on your computer, save it, and re-upload it to your root directory.