I’m also randomly having the “failed to open stream” error. When this occurs, no CSS is loaded. I can’t seem to force this error, but it shows up dozens of times a day. AO is version 2.4.4. (I’ve removed irrelevant part of the url to shorten error msg)
20190110T062301: http://www.nordicyachtworks.com/index.php
PHP Warning: file_put_contents(xxxxxxx/public_html/NordicYachtWorks/WordPress/wp-content/cache/autoptimize/js/autoptimize_snippet_0bd8cb193234a743b26238dd43756542.js): failed to open stream: No such file or directory in xxxxxxx/public_html/NordicYachtWorks/WordPress/wp-content/plugins/autoptimize/classes/autoptimizeCache.php on line 103
