In the morning the user deleted some log files to free up space and then the below mentioned error occurred. I have checked locally and all the folders are available on the server.
[18-Mar-2024 14:46:15 UTC] PHP Warning: Invalid argument supplied for foreach() in /ojs/lib/pkp/classes/i18n/PKPLocale.inc.php on line 878
[18-Mar-2024 14:46:15 UTC] PHP Warning: Invalid argument supplied for foreach() in /ojs/lib/pkp/classes/i18n/PKPLocale.inc.php on line 533