post_max_size is the largest amount of data a form may send in one go. It must be at least as large as upload_max_filesize.

Here's how #

1. Log in to DirectAdmin: open your plan in your client area and click Open DirectAdmin. You're signed in right away.
2. Open Select PHP version (under Extra Features), or type "Select PHP" in the search field.
3. Open the Options tab.
4. For post_max_size, choose a value at least as large as upload_max_filesize.

Does the page show an error about the "native" PHP version? Then first choose a regular PHP version at the top (e.g. 8.3) and click Set as current.

Stuck? Open a ticket, we're happy to help.