Showing 503 Error When I Active Autoptimize Plugin

morning @masrytech;
sorry for the error there, but it can be fixed;
first of all make sure you disable WP rocket JS/ CSS/ HTML minification features, combining minification functionality from different plugins can break stuff (minifiers are a jealous bunch)

if you’ve done that and the problem persists, you can either switch to the legacy minifiers as explained in the FAQ OR you could try the beta of Autoptimize 2.2 which _should_ fix most of the problems with crashing minifiers (the components used by AO to do the actual minification).

hope this helps,
frank

Thanks