We setup a site recently and I experienced a “Cannot decode raw data” error in Safari on iOS for both the iPhone and iPad.

We have a caching plugin installed on the site on WordPress called WP Super Cache and I immediately assumed that this had something to do with it. Clearing the cache or even disabling the plugin solved the problem.

It came down to the “Compress pages so they’re served more quickly to visitors.” setting which turns on Gzip compression using PHP ob_gzhandler when in PHP mode.

The only solution for us was to turn off this “Compress pages so they’re served more quickly to visitors.” setting for now. We tried legacy, PHP and mod_rewrite caching with different settings but nothing solved the issue other than turning off the setting.