To use Once, make sure your hosting provider is running the following software:
- WordPress 4.9 or higher.
- PHP 7 or greater. WordPress officially suggests to use PHP 7.2.
- MySQL 5.6 or greater.
Many issues you may run into such as: white screen, demo content failures when importing, empty page content and other similar issues can be related to low PHP configuration limits. The solution is to increase the PHP limits. You can do this on your own, or contact your web host and ask them to increase those limits to a minimum as follows:
max_execution_time = 120 memory_limit = 128M post_max_size = 64M upload_max_filesize = 64M max_input_time = 60 max_input_vars = 3000
Also consider upgrading your PHP version to the latest version, the newer the better.
You can check your PHP configuration limits also by installing the WordPress phpinfo() plugin and then going to Settings → PHP Info. The first column (Local) refers to your installation value, and the second column (Master) refers to the limits of your host. The latter values are often lower if you have selected a cheaper hosting package.