The Volto interface language does not switch

Development Plone 6 UI (Volto)
1

Hello!
Today, I performed a fresh installation of Plone with Volto following the instructions ("Install Plone with Cookieplone"). I noticed that the Volto interface language does not change (e.g., German, Spanish, etc.). The Volto menu items, login, and search remain in English only.

There are no issues with the classic Plone UI—everything switches instantly to the selected language.

Compilation and startup complete without errors. The Volto translation files (.po and .json) are present.

The issue affects both the public interface and the user dashboard.

Could someone try installing the latest version and check, or should I report the issue directly on GitHub?

Versions:

  • Volto: 18.10.1
  • Plone: 6.1.0
  • plone.restapi: 9.11.0
  • CMF: 3.6
  • Zope: 5.12
  • Python: 3.11.2 (main, Nov 30 2024, 21:22:50) [GCC 12.2.0]
  • PIL: 11.0.0 (Pillow)

Add-ons:

  • @plone/volto-slate: 18.2.3
  • volto-plone2025: 1.0.0-alpha.0

Small example:
Small example:1234×709 32.1 KB

2

After logging in to the VLT demo site, visit the following URL.

https://demo.plone.org/controlpanel/language

You can also edit options under Negotiation scheme. However, I'm not clear how each item is supposed to work. Our documentation of using control panels in Volto does not exist.

3

Thank you for your attention to my question.
This morning, I visited demo.plone.org and tried switching to Spanish and German. I used the language installation panel mentioned in your link. All the labels that were marked in the screenshot above changed according to the selected language. In other words, everything worked as expected.

The demo uses an earlier version of Volto (18.8.1) compared to mine (Volto 18.10.1). I decided to install the same version as in the demo on my system, but that didn’t change anything.

Next, I decided to reinstall Debian (fresh and stable) and set everything up again, but that didn’t help either. Language switching in Volto still doesn’t work. I suspect the issue might not be related to Volto itself.

Could the operating system language affect Plone and Volto?
Could you recommend an operating system where language switching definitely works?

4

I installed the English locale in Debian and set up Volto 18.8.1.
Plone 6.1.0 - the interface language does not switch.

I also noticed that in the language settings of a specific user, the field value is not saved. It is always empty after reopening.

Could Node.js affect this issue? I installed it following the instructions from:
Install Plone with Cookieplone — Plone Documentation v6.

5

To change the list of available languages in Volto you need to change a setting in Volto config.

Check our docs at Language negotiation in Volto — Plone Documentation v6

The support to use the setting in the controlpanel is coming

6

Thank you, erral Mikel Larreategi. I'm actually trying this right now. Unfortunately, the author of the document didn't specify the exact place where this should be added.

On my second attempt, I managed to change the situation, but it’s clearly not working correctly. It looks very similar to the multilingual module from the classic Plone UI, but it’s not the same.

volto2
volto21286×847 87.3 KB

It should work like on demo.plone.org, where everything functions properly from the Volto control panel.

volto3
volto31438×676 48.7 KB

7

Multilingual Support Addon brings even more chaos to Volto translations. However, the homepage of the site starts working properly.
Found here: