Troubleshooting WordPress Playground

This page covers errors from the Playground website itself, saved Playgrounds, browser storage, and WordPress boot. For Blueprint-specific errors, see Troubleshoot and debug Blueprints.

Playground looks broken

Try these first:

• Use the reload button inside the Playground toolbar instead of refreshing the browser tab. Browser refresh starts the whole Playground app again.
• Open the same URL in a private window to rule out saved-site or browser-storage state.
• Disable browser extensions that block JavaScript, WebAssembly, storage, workers, or network requests.
• Check browser developer tools for Console and Network errors.
• If the URL includes ?site-slug=..., try removing that query parameter to start a fresh unsaved Playground.

A clean site says the MySQL extension is missing

You may see a WordPress error page like this:

Your PHP installation appears to be missing the MySQL extension which is required by WordPress.

In Playground, this usually means WordPress did not load the SQLite integration that lets WordPress run without MySQL. Playground runs WordPress in WebAssembly and uses SQLite instead of a MySQL server.

Try these steps:

• Start a fresh unsaved Playground at https://playground.wordpress.net/ to confirm the public site can boot.
• If the URL includes a saved site, remove ?site-slug=... and load a new temporary site.
• If this happened after importing a ZIP, confirm the import did not include a custom wp-content/db.php that overrides Playground's SQLite setup.
• If this happened in the CLI, do not use --skip-sqlite-setup unless you provide your own database integration.
• If this happened with a Blueprint, see the Blueprint troubleshooting page.

If you are writing a Blueprint and need to add the SQLite integration plugin, plugins goes at the top level:

{
	"preferredVersions": {
		"php": "8.3",
		"wp": "latest"
	},
	"plugins": ["sqlite-database-integration"],
	"steps": [
		{
			"step": "login",
			"username": "admin"
		}
	]
}

Error connecting to the SQLite database

This means Playground loaded the SQLite integration, but WordPress still could not connect to the database.

Common causes:

• A saved Playground's browser storage is stale or incomplete.
• An imported site ZIP contains an incompatible database file or database drop-in.
• A mounted local directory is missing files that WordPress needs.
• Browser storage was cleared, evicted, or blocked.

Recommended recovery:

1. Start a fresh unsaved Playground without site-slug.
2. If the fresh site works, the issue is tied to the saved site or imported archive.
3. Export any accessible files from the broken saved site using the File Browser or local directory copy, if available.
4. Re-import the site into a new Playground, or rebuild it from its Blueprint.

NotAllowedError

NotAllowedError usually means the browser blocked an operation that requires user permission or a supported browser context. In Playground, this often relates to saved sites or local directory access.

You may see this exact message:

The request is not allowed by the user agent or the platform in the current context.

Try:

• Open Playground in a normal top-level browser tab, not inside a restricted iframe.
• Reopen the site from the Playground Saved Playgrounds panel.
• If the site was saved to a local directory, import or save the directory again.
• Confirm the browser supports the file or storage API being used. Chrome and Edge generally have the broadest local directory support.
• Check whether private browsing mode, enterprise policy, or browser settings block storage access.

NoModificationAllowedError

NoModificationAllowedError means the browser or filesystem refused a write. This can happen when a saved local directory became read-only, permission was lost, or browser storage is unavailable.

You may see this exact message:

An attempt was made to write to a file or directory which could not be modified due to the state of the underlying filesystem.

Try:

• Save a copy to a different local directory.
• Check that the target folder still exists and is writable.
• Avoid system-protected folders or synced folders that temporarily lock files.
• Start a fresh unsaved Playground if you only need a temporary test site.
• Use Playground CLI for local development that needs reliable filesystem persistence.

Saved Playground cannot reload

Saved Playgrounds are stored in browser storage or in a local directory you selected. They are not hosted on a remote server.

If a saved Playground cannot reload:

• Confirm you are using the same browser and browser profile where it was saved.
• Check whether browser data was cleared or storage was disabled.
• If the site was saved to a local directory, confirm the directory still exists and has not moved.
• If the URL includes ?site-slug=..., remove it to start a fresh unsaved site.
• Recreate the saved site from its original Blueprint or import ZIP if storage was lost.

Browser storage and persistence

An unsaved Playground is temporary. A browser refresh, tab close, storage cleanup, or browser profile change can remove its state.

Use the Save button before doing meaningful work. For longer-running local development, prefer the Playground CLI, which persists site files on disk.

The refresh button inside the Playground toolbar reloads WordPress while keeping the current Playground runtime. The browser refresh button reloads the full app and can discard unsaved changes.

When to start fresh

Start a fresh unsaved Playground when:

• You only need to test whether the public Playground site is working.
• The URL points to a saved site-slug that no longer loads.
• You are debugging whether an error comes from Playground itself or from a plugin, theme, Blueprint, or imported site.
• Browser storage or local directory access is suspected to be broken.

Use this URL for a clean site:

https://playground.wordpress.net/

Report a Playground issue

If the problem reproduces on a fresh unsaved Playground, please open an issue and include:

• The full Playground URL.
• The browser and operating system.
• Whether you used a saved site, imported ZIP, Blueprint, local directory, or CLI.
• The exact error name and message.
• Console and Network details from browser developer tools.