Download the current installable theme ZIP from the developer account or your project repository. A purchase bundle may contain documentation, licensing files and several ZIPs; that outer bundle is not necessarily the theme WordPress expects. Check whether the design is a child theme that requires a separate parent theme.

Back up an existing website and use staging for a significant design change. Keep commercial licence information securely and understand how future updates will be delivered.

1. Open Appearance > Themes > Add New Theme and choose Upload Theme.
2. Select the installable ZIP and choose Install Now. Wait for the result rather than starting another upload immediately.
3. If WordPress identifies an existing theme and offers replacement, compare the installed and uploaded details carefully. Replacing files can overwrite direct code changes.
4. Install any required parent theme from its legitimate source. Preview or activate the new theme on staging and follow the developer's configuration instructions.
5. Activate it on the live site only after reviewing your own pages and completing the planned backup.

Verify navigation, page templates, responsive layouts and key forms. A successful upload does not prove the theme is configured or compatible with every plugin.

A missing stylesheet error commonly means the wrong ZIP was selected, although an incomplete package can produce a similar result. An upload size error relates to server or PHP limits; ask us to review the relevant service rather than changing unrelated settings. If activation causes a fatal error, retain the message and use the recovery route or ask for help restoring the previous working theme. Do not delete the only known working theme during troubleshooting.

• Installing a WordPress theme from the theme directory
• Deleting an unused WordPress theme safely
• Planning and checking your WordPress backups
• Understanding Site Editor styles versus theme file changes

• Working with themes