WordPress sites using Elementor Pro with Advanced Custom Fields (ACF) frequently encounter these PHP warnings in error logs:
PHP Warning: Undefined array key 0 in elementor-pro/modules/dynamic-tags/acf/tags/acf-image.php on line 40
PHP Warning: Undefined array key 1 in elementor-pro/modules/dynamic-tags/acf/tags/acf-text.php on line 33
Root Cause
The issue stems from a compatibility problem between ACF and Elementor Pro’s dynamic tag system. Specifically:
ACF Image fields return arrays with ‘ID’ (uppercase) but Elementor expects ‘id’ (lowercase)
- The list() function in both files expects a numerically indexed array [0, 1] but sometimes receives empty or malformed arrays
- Empty or null ACF values cause the Module::get_tag_value_field() method to return inconsistent data structures
Impact
- Error log spam (hundreds of entries per minute)
- Increased server load from excessive I/O operations
- Poor user experience when errors are displayed on frontend
- Performance degradation on sites with many ACF fields
The Solution
Add this code snippet to your theme’s functions.php or use a code snippets plugin :
How It Works
- Error Suppression: Catches and suppresses the specific ACF dynamic tag errors without affecting other PHP warnings
- Key Mapping: Adds the missing ‘id’ key to ACF image arrays by copying from ‘ID’
- Value Consistency: Ensures ACF fields return consistent data types that Elementor can handle
- Performance Optimization: Eliminates excessive error logging that impacts server performance
Verification
After implementing the fix:
- Check error logs – ACF-related errors should disappear
- Test dynamic content – All ACF fields should display correctly
- Monitor performance – Reduced I/O operations and CPU usage
- Validate frontend – No error messages should appear to users
Compatibility
- WordPress: 5.0+
- Elementor Pro: All versions
- ACF: Free and Pro versions
- PHP: 7.4+
Why This Matters
Neither ACF nor Elementor Pro have officially addressed this compatibility issue, leaving developers to find their own solutions. This fix provides a clean, performance-optimized resolution that doesn’t interfere with normal functionality while eliminating the error spam that plagues many WordPress installations.
This solution has been tested on production environments and provides a reliable fix for one of the most common WordPress compatibility issues between ACF and Elementor Pro.





