Default PHP limits are set for ordinary websites, not shops.
RECOMMENDED VALUES
cPanel > MultiPHP INI Editor, select your domain, and set:
memory_limit: 256M max_execution_time: 300 upload_max_filesize: 64M post_max_size: 64M max_input_vars: 3000
max_input_vars matters more than people expect. A product with many variations, or a settings page with many fields, silently fails to save when it is too low.
PHP VERSION
cPanel > MultiPHP Manager. Use PHP 8.1 or 8.2. WooCommerce is noticeably faster on current PHP, and older versions no longer receive security patches.
Check WooCommerce > Status before switching; it flags anything incompatible.
REQUIRED EXTENSIONS
curl, gd or imagick, mbstring, zip, intl, soap and bcmath. Enable any missing ones under cPanel > Select PHP Version > Extensions.
CHECKING
WooCommerce > Status shows the active values and flags anything below recommendation. Work down that page until the warnings clear.
