Este plugin no se ha probado con las últimas 3 versiones mayores de WordPress. Puede que ya no tenga soporte ni lo mantenga nadie, o puede que tenga problemas de compatibilidad cuando se usa con las versiones más recientes de WordPress.
With all the fuss about "pretty permalinks" in WordPress for so many years I find it surprising that WordPress is still withholding from its users an option to set a custom permalink/slug for the search results page.
There are quite a number of plugins around which — at least — do away with the ugly /?s=search+terms. But the ones I've seen so far do not do the one thing I'm sure everybody has been expecting to see as a WordPress core feature for years, and that is to offer an option on the Permalinks Settings page so that everyone is not stuck with the hardcoded /search/ as only choice.
Luckily this is now a thing of the past. After installing and activating WP SEO Search, you can now set your own search results base (slug) on the Permalinks Settings page.
Many thanks to Angelica Costa for taking this long awaited extra step!
P.S.: Regarding WP Multisite - The plugin can be activated network wide. Setting a custom search base can be/needs to be done per site. Currently the standard slug is /search/, regardless of the language in use.