How to Fix Meta Box Datepicker and Language Localization Issues

Many WordPress users who utilize the Meta Box plugin for creating custom fields encounter issues with datepicker localization and language file naming. These problems often prevent the datepicker interface and plugin text from displaying in the correct language, such as French, Spanish, Dutch, or Russian. This guide explains why these issues occur and provides practical solutions based on community-reported fixes.

Common Localization Problems

Based on user reports, the most frequent localization issues with Meta Box include:

• Datepicker displaying in English instead of the site's configured language
• Missing or incorrectly named language files (e.g., nl.mo instead of nl_NL.mo)
• Datepicker i18n files with incorrect naming conventions (e.g., jquery.ui.datepicker-nl.js instead of jquery.ui.datepicker-nl-NL.js)
• Encoding issues displaying strange characters instead of proper text
• Inline date fields initially showing in English before switching to the localized language

Why These Localization Issues Happen

The Meta Box plugin attempts to load language-specific files based on your WordPress configuration (WPLANG setting in wp-config.php). However, the plugin expects these files to follow specific naming conventions that sometimes don't match what's actually included in the plugin's distribution.

For datepicker localization, the plugin constructs the filename using this pattern: jquery.ui.datepicker-[locale].js where [locale] is derived from your WordPress language setting. If your language files don't follow this exact naming convention, the localization will fail.

Solutions for Meta Box Localization Issues

Solution 1: Rename Language Files

Many users have reported success by simply renaming the language files to match what Meta Box expects:

1. Navigate to your Meta Box plugin directory: /wp-content/plugins/meta-box/
2. For datepicker localization, check the files in /js/jqueryui/datepicker-i18n/
3. Rename files to follow the pattern: jquery.ui.datepicker-[language_COUNTRY].js (e.g., for Spanish: jquery-ui-datepicker-es-ES.js, for French: jquery.ui.datepicker-fr-FR.js)
4. For plugin translation files, ensure they follow the pattern: [language_COUNTRY].mo (e.g., nl_NL.mo instead of nl.mo)

Solution 2: Conflict Testing

If you're experiencing encoding issues or strange characters (like in Russian):

1. Temporarily deactivate all other plugins except Meta Box
2. Switch to a default WordPress theme (Twenty Twenty series)
3. Clear all caches (browser, server, and any caching plugins)
4. Check if the issue persists
5. Reactivate plugins one by one to identify conflicts

Solution 3: Check Inline Date Field Behavior

For inline date fields that initially appear in English before switching to your language:

This is a known issue where the datepicker doesn't initialize with the correct localization immediately. The Meta Box development team has been made aware of this behavior for future updates. As a temporary workaround, you might need to manually trigger a refresh after the page loads.

Preventing Future Issues

To avoid localization problems after plugin updates:

• Keep notes of any file modifications you make
• Consider using child themes or custom plugin functionality to maintain your changes
• Check the plugin's changelog before updating to see if localization issues have been addressed

Many of these localization issues have been reported to the Meta Box team, and some fixes have been implemented in recent versions. However, depending on your specific language requirements, you may still need to apply these manual solutions.