LM-X performs checks to verify that environment variables (for example LC_ALL or LANG) are set. If they are not set, then LM-X sets them to "C". However, if the environment variable does not point to a valid locale, then LM-X does not perform any action, because it considers such variable to be set. When LM-X is unable to find a valid locale, you will see an error similar to the following:
locale::facet::_S_create_c_locale name not valid
This is not an LM-X error, but rather indicates a problem with your local machine caused by a misconfigured locale.
You can use the following command to output information about the current locale environment on your system:
locale
To check if current locales are supported by your operating system, run the following command:
locale -a
To install the locale, run:
sudo locale-gen name_of_the_locale
For more information about locales, please refer to official Ubuntu documentation, or see the documentation relevant for your operating system.