Locale switches back to default after `setLocale`

Version

nuxt-i18n: 6.13.12 nuxt: 2.12.2

Nuxt configuration

mode:

• universal
• spa

Nuxt-i18n configuration

  i18n: {
    lazy: true,
    langDir: '../locales/',
    locales: ..., // some dynamic code here
    strategy: 'prefix',
    defaultLocale: 'en',
    detectBrowserLanguage: {
      // If enabled, a cookie is set once a user has been redirected to his
      // preferred language to prevent subsequent redirections
      useCookie: true,
      // Cookie
      cookieKey: 'language',
      cookieSecure: true,
      // Set to always redirect to value stored in the cookie, not just once
      alwaysRedirect: true,
      // If no locale for the browsers locale is a match, use this one as a fallback
      fallbackLocale: 'en',
    },
  },

Steps to reproduce

1. I am on locale en
2. I select cs via $i18n.setLocale('cs');
3. cookie is successfuly updated to cs
4. nuxt-auth is redirecting to /cs
5. after next boot something - and I can’t find it in the code (I put debugger to all places in plugin.main.js where redirection happens) - is redirecting back to /en
6. on visit of /en cookie is set back to en which is expected

What is Expected?

The redirect back to default locale does not happen

[MartinMalinda]

@rchl

I did some more debugging and docs reading and the issue is now clear to me.

It’s the combination of alwaysRedirect and detectBrowserLanguage and useCookie.

When I setLocale that causes a redirect, after redirect the detectBrowserLanguage will prefer the browser language over the value from the cookie.

I’d expect the browser language would be used only if there’s no cookie but the priority is different. I’m not sure if this is a bug or a feature though.

And then I found out that onlyOnRoot mostly fixes the issue for me. But even still, even on / I’d expect that cookie has higher priority over browser language. Is that just me?

[MartinMalinda]

So I couldn’t reproduce in a different repo and it made me double check my main app code.

It turned out I had two cookies with same key but with different domains (somehow). I guess it was a leftover from much earlier. JsCookie.get(cookieKey) preferred it over the new one and that’s why the language was switching wrongly for me.

Sorry for the time waste! I think this can be closed.