Causes

• The URL was too long for the server to process
• At the point when a client has inappropriately changed over a POST request to a GET request with long inquiry data
• When the server is under attack by a client for exploiting security holes

Fixes

Apache:

Step 1: Enter The Configurations File

Go to the .htaccess file

Step 2: Modify The Limit

You can set the LimitRequestLine 10000

Step 3: Add The Line

If you do not had this line, then you may add a new line

Nginx:

Step 1: Enter Configuration File

Go to the /etc/nginx/nginx.conf

Step 2: Modify The Maximum Size

Set the large_client_header_buffer to the maximum size

Step 3: Save The Changes

Then save It and type the following command, sudo service nginx restart