Hey, Juan Lai

We'll probably want to take a look at your folders.json folder to see what's going on. Will you please start a ticket with our support department and include that with the ticket? Thanks!

Hello

We had the same problem. One of our customers couldn't change language to German. Same exception. We then noticed that he has a sub-folder named Entwürfe (Drafts) as sub-folder below sent-items. This caused the problem. Once we deleted this folder the language-changed worked.

Seems to be a new bug that Smartermail does not only check root-folders for name-conflicts but all folders including sub-folders

Same issue, but in Portuguese (Brazil). A folder named "Rascunhos" (Drafts) caused the problem. Folder renamed and the problem was solved. Thank you!

(portuguese) Para quem teve o idioma trocado no SmarterMail e quando tenta trocar aparece o erro "Language was not updated to prevent an email folder name conflict", verifique se não há pastas de email que já estão com o nome em português (Caixa de Entrada, Rascunho, Lixo Eletrônico, Itens Enviados...). Se tiver, apenas mude o nome (botão direito do mouse sobre o nome), por exemplo "Rascunhos1". Assim é possivel voltar para o Português (Brasil).

Thanks for your follow up on this Vitor, glad to hear that worked for you. For anyone reading this in 2021 I have referenced the original fix instructions below: 

If you get an error of "Language was not updated to prevent an email folder name conflict" when trying to change your language, it means that the user has a custom email folder with the same name as one of the default email folders, but in the language they're attempting to change to.

For example, if the user is trying to change their language to Portuguese (Brazil), and they're getting that error, it means they have one of more custom folders in Portuguese named Inbox, Deleted Items, Junk Email, Drafts, or Sent Items.

In order to change their language, you'll need to delete or rename the custom folders to something that does not match the same translation string we use when you change your language to Portuguese.

The creation of those custom folders was a bug symptom of the previous implementation of server-side language translations. It has since been corrected. Going forward, custom folders that copy the naming convention of the default folders should not be created.