Background of the issue:
I am trying to add a new language (German) to my WordPress site using WPML. I currently have French, English, and German set in Default Locale.
Symptoms:
I received a warning about 'Default locale' when I added the German language. It seems like the setup was not done correctly.
Questions:
Should I change the Default Locale for French to fr-FR, English to en-GB, and German to de-DE?
Should I update all the Default Locales?
If I change the Default Locales, will it impact the existing translations or SEO?
Are fr, en, and de valid Default Locales, or are they incorrect?
It is safe to change the Default locale of a language. Becuase it will not affect site URLs (which are handled by the Language Code field and it will not be possible to change it, because it is a unique value).
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