Hi @vmarko and thanks for working on this.

Yes, the warnings are identical, with W3TC version 2.7.2 and the latest version of WordPress and all themes/plugins updated. I did some further testing, and the first batch of warnings only appears when viewing the Performance Dashboard (/wp-admin/admin.php?page=w3tc_dashboard):

PHP Warning: Undefined array key "interval" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 15
PHP Warning: Undefined array key "since" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 18
PHP Warning: Undefined array key "interval" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 23
PHP Warning: Undefined array key "until" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 26
PHP Warning: Undefined array key "bandwidth_all" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 38
PHP Warning: Undefined array key "bandwidth_cached" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 39
PHP Warning: Undefined array key "requests_all" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 43
PHP Warning: Undefined array key "requests_cached" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 44
PHP Warning: Undefined array key "pageviews_all" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 48
PHP Warning: Undefined array key "uniques_all" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 52
PHP Warning: Undefined array key "threats_all" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 56
PHP Warning: Undefined array key "cached_tf" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 59
PHP Warning: Undefined array key "cached_ts" in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Widget_View.php on line 59

If I go into Extensions > Cloudflare > Settings and Reauthorize, this batch of warnings ceases.

On some of my 80 sites, like my test site (wordpress.pillerdesigns.com), the other warning appears to have resolved itself (without having to Reauthorize):

PHP Warning: Undefined array key 1 in /wp-content/plugins/w3-total-cache/Extension_CloudFlare_Plugin.php on line 390

Maybe it helps that this testing site hasn’t had W3TC continuously active for the past year. However, on many of my sites, like onadrapery.com and bobwells.org, this warning continues to appear once on every front-end page load and 1-4 times or more on every back-end page load or request. I have tried reauthorizing after deactivating/reactivating the Cloudflare extension and then purging all caches, but the warning persists. I also tried deactivating/reactivating W3TC. Interestingly, sometimes clicking Deactivate under Cloudflare on the Extensions page just reloads the page, and it takes a few tries to actually deactivate this extension. Also the warning appears with every front-end page load when logged in but only sometimes when refreshing the homepage without being logged in.

I can give you access to my testing site, if you’d like, where I haven’t yet done the reauthorization to clear the first batch of errors. My hope is that both sets of warnings can be resolved without having to reauthorize 80 sites. The reauthorization is especially annoying because the Cloudflare domains are split into 5 pages, so I can’t simply scroll to click the associated domain’s radio button. On sites that still show the second warning, this warning also appears when clicking to a new page of results in your Cloudflare authorization popup.

Finally, this is probably a separate issue, but in case it helps, on a couple of my sites, like flowscreens.com, I have never been able to get rid of the “One or more plugins have been activated or deactivated, please [empty the page cache] [hide this message].” notification, no matter how many times I click [empty the page cache] or [hide this message]. This has been the case for years, even after deleting the plugin and reinstalling without importing a backup of my settings. I believe I reported this is another ticket a long time ago.

• This reply was modified 1 month, 2 weeks ago by Zade. Reason: added more information