Append into settings.php
$conf = array( 'cache' => '0', 'preprocess_css' => '0', 'preprocess_js' => '0', 'block_cache' => '0', 'page_compression' => '0', );
Then start investigation which one is cause of the error
Source: https://drupal.stackexchange.com/questions/78764/content-encoding-error-after-enabling-cache-aggregation-and-compression