Could not verify if the cache was enabled. Turn on logging to find the reason.

Hi there,

I am having trouble enabling the page cache feature. I get this error on the plugin page “Could not verify if the cache was enabled. Turn on logging to find the reason.”

And I get these two errors in the browser console:

Object { type: “warning”, message: “unlink(/wp-content/advanced-cache.php): Permission denied”, file: “wp-content/plugins/wp-optimize/cache/class-wpo-page-cache.php”, line: 375, stack: (5) […], component: “Plugin: wp-optimize” }
query-monitor.js:324:14

Object { type: “warning”, message: “file_put_contents(/wp-config.php): failed to open stream: Permission denied”, file: “wp-content/plugins/wp-optimize/cache/class-wpo-page-cache.php”, line: 679, stack: (6) […], component: “Plugin: wp-optimize” }

I do not understand why the first error Unlink happens with advanced-cache.php. That file has the code that the plugin said it should have. The file permissions for advanced-cache.php are Group: www-data. Owner: Me. Permissions: 0664 (owner group and others have R permission)

For the second error, I understand that it is trying to write the following line in wp-config.php: define( ‘WP_CACHE’, true );
I already have that written in wp-config.php. The file permissions for wp-config.php are Group: www-data. Owner: Me. Permissions: 0640 (owner and group have R permission)

Additional info just to make sure I’m doing this right:
both wp-content/cache/ folder and wp-content/wpo-cache folder have 2775 permissions and files inside are 0664.

How do I fix this problem? Thanks in advanced.