“414 Request-URI Too Large” error happens when the url is tool large.
Usually when we select multiple users in WordPress and apply bulk delete action on selected users; WordPress will form the url with all the selected users and send the url to the server to delete the selected users from WordPress database. There is a problem here; there is a limit in length of the url. When we select large number of users, and apply delete operation, WordPress will form the url with these large number of selected users; hence it exceeds the length of the url which cause “414 Request-URI Too Large” error.
To resolve this, always select minimum number of users; instead of large number and do the bulk delete operation. Which will ensure the length of the url will be within the limit.
To control the number of users displayed on “Users” page is, follow the below steps.
Step 1. On “Users” page, click on “Screen Options” link; which is usually on top of “Search Users” button. WordPress will display “Show on screen” panel.
Step 2. From “Show on screen” panel, enter the number in Users field. This way we can tell WordPress to display the mentioned number of users on “Users” page. Then click on Apply button.
Observe that the WordPress will refresh the “Users” page and display the mentioned number of users on the page.
Step 3. Now you can try selecting the users and apply bulk delete operation. WordPress will successfully delete the selected users from WordPress database.