Unable to import large mbox file in cPanel's Webmail

Symptoms

When attempting to import a mbox mailbox file in cPanel's Webmail, the error "No file Found" or "No Input File" is returned. The PHP error log file located in the user directory will also return similar errors.

File: /home/cPaneluser/logs/.php.error.log

[29-Apr-2022 22:39:53 America/Chicago PHP Warning:  POST Content-Length of 226216813 bytes exceeds the limit of 57671680 bytes in Unknown on line 0
[29-Apr-2022 22:42:28 America/Chicago] PHP Warning:  POST Content-Length of 226216813 bytes exceeds the limit of 57671680 bytes in Unknown on line 0
[29-Apr-2022 22:45:28 America/Chicago] PHP Warning:  POST Content-Length of 226216813 bytes exceeds the limit of 57671680 bytes in Unknown on line 0

Description 

cPanel's Webmail applications will return "No File Found" or "No Input File" during file uploads when settings in the 3rdparty php.ini aren't sufficient for the upload file. Increasing the 3rdparty php.ini limits will generally resolve the issue.

Workaround

Increase the following PHP values to allow the file to upload and process in webmail applications.

File: /usr/local/cpanel/3rdparty/etc/php.ini

upload_max_filesize
post_max_size
memory_limit

Note: If cPanel's PHP-FPM service is in use, be sure to restart after applying the changes.

/scripts/restartsrv_cpanel_php_fpm
/scripts/restartsrv_cpsrvd

You can find additional details in the following article:

How do I modify the PHP ini PHP value for one of the web applications such as PHPMyAdmin or Roundcube