If you see the error message “Undefined” when you try to add a template:
- Upgrade your PHP version to PHP7 (backup your website before)
- In some cases, the latest version of PHP may cause undefined errors. Although staying up to date with PHP versions is often a good idea, it may cause problems for edge cases. Downgrade to a PHP version one version lower than the latest if this occurs.
- Ask your hosting company to increase the timeout value of your server
- Ask them also to check the database encoding
- Verify that it is not due to a plugin conflict by deactivating all your plugins besides Elementor and Elementor Pro. If this solves the issue, reactivate them one by one to find the culprit.
- Check if it is not due to a conflict with a browser add-on by editing in incognito mode with your browser.