Inspect the installed PHP capability
Open the website PHP tab or PHP Management → MultiPHP Manager. Select only a version returned as supported by the live capability response. The reviewed source qualification covers PHP 8.3; it does not establish that every server has every PHP release. Installed extensions are an inventory, not an extension installer.
The version switch is POST /v1/websites/{id}/php-version with php_version and the current website revision. Follow the durable operation and verify the site's actual PHP response afterward. Preserve the existing INI and MIME configuration while changing versions.
Per-website INI editor
Enter supported name=value lines in Validated PHP INI overrides. Obtain allowed fields through GET /v1/php-ini-fields; unsupported arbitrary directives must be rejected. Review memory/resource values against account enforcement instead of assuming an INI value increases the account cgroup or package allowance. Current website edits send the parsed php_ini object as part of the revision-guarded website plan.
MIME response types
Customer Advanced → MIME Types opens the website's supported MIME editor. It uses the current versioned policy rather than allowing raw Nginx/Apache text. Review extension/type mappings and their validation feedback, then submit through website create/modify. Missing or null changes preserve existing mappings; an explicit empty mapping clears them. The source implements these controls, but its newer renderer/file-recovery path has separate installed qualification requirements. Do not hand-edit installed configuration to force source support.
Custom errors and handlers
Error Pages maps allowed status codes to an account-relative custom error page. Check that the file exists and renders safe content before testing an actual error. PHP is selected by supported website runtime; the general Apache Handlers editor is not implemented. Per-site HTTP/2/HTTP/3 policy, response compression controls, arbitrary multi-version package installation and global PHP-default inheritance remain unimplemented in this checkpoint.
Verify and diagnose
After a successful operation, test ordinary static content and the intended PHP handler without exposing phpinfo() publicly. Read the website/PHP error log and actual capability state. An unavailable version is not resolved by typing a different version into the API. On a configuration failure, keep the operation reference, exact reviewed revision and sanitized error. Do not disable confinement, replace shared FPM packages or overwrite unknown configuration. Server service restart controls are separately protected and affect shared workloads.