If your WordPress admin suddenly starts showing raw JSON or code instead of usable input fields—especially after a server upgrade—the issue is often tied to PHP compatibility.
In this case, a site experienced a critical failure where custom “ACF-like” fields stopped rendering, preventing editors from managing content.
The root cause was a PHP 8 incompatibility inside a custom theme framework affecting dynamic field rendering.
Issue Background
The site used a custom WordPress theme with a proprietary field system similar to ACF. After upgrading from PHP 7.4 to PHP 8, multiple admin interfaces broke.
- Content editing areas showed raw JSON/code
- File upload fields lost functionality
- Custom resource selection interfaces disappeared
Diagnosis
PHP 8 incompatibility in theme code
A theme-level component responsible for rendering repeatable fields and dynamic UI elements failed due to deprecated or incompatible PHP syntax.
Instead of rendering input fields, the system output raw stored data.
Custom field system (not ACF)
The site used a proprietary field framework, not the ACF plugin, so standard troubleshooting methods did not apply.
UI rendering failure
The field system could not interpret definitions, resulting in JSON or structured data being displayed instead of usable interfaces.
Resolution Steps
Step 1: Identify the rendering component
Locate the theme files responsible for generating admin UI elements and repeatable fields.
Step 2: Update for PHP 8 compatibility
Fix deprecated functions, adjust type handling, and correct array/object access issues.
Step 3: Test in staging
Verify that fields, file uploads, and dynamic UI elements render correctly in a staging environment.
Step 4: Deploy to production
Apply the fix to the live site and keep a backup of the original file.
Step 5: Validate all content areas
Ensure all custom post types and repeatable fields are functioning properly and no raw code is displayed.
Final Outcome
- Admin UI fully restored
- Editors regained content control
- Custom fields function correctly on PHP 8
- No system rebuild required
If your WordPress admin is showing broken fields after a PHP upgrade, contact Freshy for expert troubleshooting and compatibility fixes.
