How to fix this gtmetrix error

[alfonso99]

I'm getting this gtmetrix error and don't know how to fix it. i would appreciate any help.

The following resources are missing a cache validator. Resources that do not specify a cache validator cannot be refreshed efficiently. Specify a Last-Modified or ETag header to enable cache validation for the following resources:

 

[dalem]

add
## EXPIRES HEADER CACHING ##
<IfModule mod_expires.c>


to your .htaccess

How to Fix the "Specify a Cache Validator" Warning

Find out how to fix the "Specify a Cache Validator" warning on your WordPress site that you see in Pingdom, GTmetrix, and PageSpeed Insights.

kinsta.com

 

[cPanelLauren]

The advice provided by @dalem is correct and for the moment I'll let the 3rd party link remain but do keep in mind @dalem that 3rd party links are not encouraged in the forums.