Hello,
Sorry or the delay.
It seems that you’ve a Plugin that required WP_CACHE constant to be defined.
WP Config File Editor currently is not being support any custom (created by Plugins) constants, only WordPress constants is being supported. The Help box tells that “you will lose any custom changes you’ve in the config file once you saved it”.
A simple solution is by Go To WP Config File Editor Dashboard page, Scroll down, Click Preview, Add define(‘WP_CACHE’, true); in a separated line after WP_DEBUG constant.
Let me know if you still have a problem
hope this helps.
Regards,
AHMeD