Symptoms
Litespeed extension can not be opened from Plesk > Extensions > My Extensions > Litespeed > Open with the below error on Plesk Obsidian 18.0.50:
Exception Caught - Warning: Undefined array key "REMOTE_ADDR" in /usr/local/psa/admin/plib/modules/litespeed/library/PleskEscalate.php on line 1488
Cause
Plesk was switched to PHP 8.0:
# sw-engine -v
PHP 8.0.27 (cli) (built: Jan 14 2023 15:19:43) ( NTS )
Copyright (c) The PHP Group
And Litespeed extension is not compatible with PHP 8.0.
Resolution
The new version of the LiteSpeed extension - 1.4.11-0 - has been prepared by the vendor.
Update the Litespeed extension.