Fix Perl Setting Locale Failed Error in Debian/Ubuntu

When installing software on Debian or Ubuntu systems, you might encounter Perl locale warnings indicating that your system’s language settings are not properly configured. These errors don’t prevent installation but can be annoying when repeatedly displayed during package installations or updates. The root cause is typically missing locale configurations or improperly set LANG or LC_* variables.

# locale-gen en_US.UTF-8 en_GB.UTF-8 && update-locale

Understanding the Error

$ apt-get install [package-name]
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = "en_US:en",
	LC_ALL = (unset),
	LC_CTYPE = (unset),
	LC_NUMERIC = (unset),
	LC_COLLATE = (unset),
	LC_TIME = "en_GB.UTF-8",
	LC_MESSAGES = (unset),
	LC_MONETARY = (unset),
	LC_ADDRESS = (unset),
	LC_IDENTIFICATION = (unset),
	LC_MEASUREMENT = (unset),
	LC_PAPER = (unset),
	LC_TELEPHONE = (unset),
	LC_NAME = (unset),
	LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US.UTF-8").
perl: warning: Setting locale failed.

Solution Explained

The solution involves generating the missing locales and updating the system locale settings. The locale-gen command creates the necessary locale files in the system, while update-locale refreshes the system configuration. This approach properly configures both the en_US.UTF-8 locale (used for most system settings) and en_GB.UTF-8 locale (specified in LC_TIME). After running these commands, Perl will be able to find the required locale data files and properly format dates, times, currency, and other region-specific information.

Examples

1. Fixing a specific locale issue: When you need only the en_US.UTF-8 locale

   # locale-gen en_US.UTF-8 && update-locale LANG=en_US.UTF-8

   This approach focuses solely on generating and setting the en_US.UTF-8 locale, which is sufficient if you don’t need British date formats or other regional settings.

2. Setting consistent locales: Setting LC_ALL to eliminate mixed locale settings

   # locale-gen en_US.UTF-8 && update-locale LC_ALL=en_US.UTF-8

   Using LC_ALL overrides all individual LC_* variables, ensuring consistent behavior across all localization categories. This is useful when you’re experiencing conflicts between different locale settings.

Additional Notes

• You must have root privileges to generate locales – use sudo if you’re not logged in as root.
• Some cloud or minimal installations may not have the locales package installed – run apt-get install locales first if locale-gen isn’t found.
• For a complete solution in automated environments, consider adding export LC_ALL=C.UTF-8 to your /etc/environment file to prevent these warnings in scripts and automated processes.