BugWP logo BugWP
Back to Community
Home / Community / Plugin → Cmb2

Troubleshooting CMB2: Why Custom Field Data Disappears and How to Fix It

32 threads Sep 7, 2025 Plugin → Cmb2

Content

One of the most disconcerting issues you can encounter with CMB2 is the sudden and unexplained disappearance of your custom field data. This problem can manifest in several ways: data vanishing from the database, fields not saving new values, or meta being deleted when conditions change. Based on community reports and common pitfalls, this guide will help you diagnose and resolve these frustrating data loss issues.

Common Causes of Data Disappearance

The threads reveal several root causes for CMB2 data loss:

  • Incorrect URL Migration: When moving a site from localhost to a live domain, performing a naive find/replace in the database can corrupt serialized data in post meta, causing WordPress to drop the entire meta value.
  • Conflicting Hooks or Code Logic: Conditional logic that shows/hides fields based on taxonomies or other criteria can sometimes trigger the saving of empty values, overwriting existing data.
  • Improper Field Deletion: For 'file' field types, manually deleting the URL from the input field instead of using the 'Remove' button can leave associated meta data (like the attachment ID) orphaned in the database.
  • Caching Conflicts: Aggressive object caching (e.g., Memcached) can sometimes serve stale data to save hooks, causing operations to use old field values instead of new ones.
  • Unsanitized Input or Mod_Security: Server-level security modules like Mod_Security can strip HTML content from fields like 'textarea_code', preventing it from being saved correctly.

How to Troubleshoot and Fix the Issues

1. Safely Migrate Your Site

Never use a simple SQL query to find/replace URLs in the wp_postmeta table. Serialized data will break. Instead, use a dedicated migration tool like WP Migrate DB or All-in-One WP Migration, which handle serialized data safely.

2. Audit Your Conditional Field Logic

If fields appear or disappear based on user selection (e.g., a taxonomy term), ensure your code does not save the metabox group when its fields are not present. When a metabox's fields are not rendered, they are often not submitted in the save process, which can result in their meta values being deleted. Review your conditionals to ensure data persistence is handled correctly.

3. Use the Correct Method to Delete Values

For file and image fields, always use the dedicated 'Remove' button or the 'X' icon next to the file preview to clear the field. Manually deleting the text from the input field will not properly clear all associated meta data.

4. Disable Caching for Debugging

If you suspect a caching issue is causing save hooks to receive old data, temporarily disable object caching (e.g., Memcached, Redis) to see if the problem resolves. If it does, work with your hosting provider to configure the cache to bypass the WordPress admin or specific post-saving routines.

5. Check Server Security Rules

If rich text or code fields fail to save, check your server's error logs for messages from Mod_Security or similar security software. You may need to whitelist specific rules or adjust your server configuration to allow the content you are trying to save.

6. Verify Your Field Registration Code

Some problems, like select or radio button values not saving, can stem from incorrect field configuration. Double-check that your field IDs are unique and that your add_field arguments are properly formatted. Inconsistent id values can create unpredictable behavior.

Conclusion

Data loss in CMB2 is rarely a bug in the core plugin itself but is almost always caused by external factors: unsafe database operations, conflicting code, server settings, or improper use of the fields. By methodically working through these common causes, you can identify the source of your problem and implement a reliable solution to keep your data secure.

Related Support Threads Support