Languages - How do I fix this "Installer unable to find language files" error I am getting

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A critical error has occurred.

This installer was unable to find the installer's language file or files. They should be found under:
/forum/Themes/default/languages

In some cases, FTP clients do not properly upload files with this many directories. Please double check to make sure that you have uploaded all the files in the distribution. If this does not help, please make sure this install.php file is in the same place as the Themes directory.

Alternatively, the languages directory has become corrupt during upload. If this is the case, try uploading it again. If it still does not work, try another FTP client, or another method.