Is Polylang compatible with multisite ?

Yes it is.

Is Polylang compatible with the EU cookie law ?

Yes it is. Polylang uses language preference cookies to remember the language selected by the user when he comes back to visit again the website. This is allowed by the EU cookie law.

I activated the plugin and my posts are not displayed any more

You MUST define a language for all your posts and pages otherwise they will not pass the language filter…

I activated the plugin and my categories and post tags are not displayed any more

You MUST define a language for all your categories and post tags otherwise they will not pass the language filter…

My theme or some plugin is not translated

There are two main reasons for this to occur:

  1. Your theme or plugin may not be translated (no or incomplete .po/.mo files). You can use the plugin Codestyling Localization to make the translation.
  2. Your theme or plugin may not be compatible with the Polylang option “The language is set from content”. Try setting the language from the directory name.

Is it possible to use a static front page ?

Yes. You have to create one page per language. Set translations as usual and then go to the WordPress ‘Reading settings’ panel. Check ‘Front page displays a static page’ and choose one of the page you have just created (the language doesn’t matter). Do the same for posts page if you use posts.
Then, if you want that the url looks like instead of, just go in the languages settings panel and check the option ‘Redirect the language page to the homepage’.

Not all my widget titles are listed in the strings translation table

If you enter a title in the widget options and this title is not listed in the translation table, it is most likely because the widget uses the old Widget API (WP < 2.8). Obviously the advantage for the widget is to be compatible with WordPress older than 2.8 but unfortunately, there is no way to make Polylang automatically compatible with all widgets which use this old API.
It is however possible to make them compatible for people who have some PHP skills, using the Polylang API functions ‘pll_register_string’ and ‘pll__’.

The random header image of Twenty Eleven does not work

Most probably you uploaded the images and did not translate them. You have to either translate the images in all languages or de-activate the languages and translations management of media in Polylang settings.

A widget has no multilingual capability

WordPress 2.8 introduced a new widget API. Polylang is compatible with this API. Any widget which is compatible with older versions of WordPress should still work but will have no multilingual capability (no possibility to display it in only one language, no possibility to translate the widget title). Of course, all default widgets are supported by Polylang.

The content is displayed in only one language on backend

Polylang introduces a new menu in the admin bar on top of the admin screen. You can choose to filter the content by language or display all languages. This filter is persistent.

Setting up Nginx fastcgi_cache and Polylang homepage redirect

RavanH wrote helpful instructions on how to setup Nginx fastcgi_cache when using Polylang on the support forum.