I doubt so. I realized that my site is not running today, then i searched for “WordPress ERR_RESPONSE_HEADERS_TOO_BIG” on google and found this thread. I just tried to disable and enable it and it worked. I did not install any new update of any plugin meanwhile. Now if I look into wp, it says I have version 4.8 and IThemes Security Plugin version is 6.2.1 and it recommends me to update to 6.3.0, so if it updated in background I’d be up-to-date now.
Same problem in my instance. @PaulDoesWP’s workaround works. However I disabled Hide backend feature and then switched it on again and now it works again with this “hide” option enabled.
So only disabling and reenabling worked for me just fine.
