I have a site that is running 8.5.4 thats been upgraded from 5.7.13. When I go to the page with an Express Form on it, it presents this error. If I delete the application/files/cache/expensive folder. It rebuilds and works... for so long, then I get this error again.

Exception Occurred: /home/mywebsite/public_html/updates/concrete5-8.5.4/concrete/src/Cache/Driver/FileSystemStashDriver.php:46 file_put_contents(/home/mywebsite/public_html/application/files/cache/expensive/0fea6a13c52b4d47/25368f24b045ca84/38a865804f8fdcb6/57cd99682e939275/2ddb27c5cdf0b672/745d4c64665be841/b50df10bac237e48/2f4ef6640e3e0da9.php): failed to open stream: Permission denied (2)

Site is on cPanel CentOS 7 hosting with PHP 7.2.

Any ideas on what's going on here?

Thanks!