WordPress ACF PHP Fields back to Admin with JSON • Works with newer ACF versions

functions.php

<?php 

// This script allows you to get your ACF PHP Fields back in the Admin
$json = "";

// get all the local field groups 
$field_groups = acf_get_local_field_groups();

// loop over each of the gield gruops 
foreach( $field_groups as $field_group ) {

  // get the field group key 
  $key = $field_group['key'];

  // if this field group has fields 
  if( acf_have_local_fields( $key ) ) {

    // append the fields 
    $field_group['fields'] = acf_get_fields( $key );

    $json .= json_encode( $field_group, JSON_PRETTY_PRINT );
  }

  // save the acf-json file to the acf-json dir 
  acf_write_json_field_group( $field_group );
  
}

// (optionnal) Echo json to see output
echo "<pre>$json</pre>";
    
    
// (Optionnal) Change ACF JSON export directory
// Also allow to auto-export groups when modified
// You should keep this hook at anytime
function my_json_save_groups( $path ) {
  $path = get_stylesheet_directory() . '/acf-json';
  return $path;
}
add_filter( 'acf/settings/save_json', 'my_json_save_groups' );

This script allows you to get your ACF PHP Fields back in the Admin.

1. Execute this script once to export all fields to JSON fields
2. You'll find them in a acf-json directory in your theme (create the folder manually if nothing happens)
3. Go to ACF > Tools > Import and import theses files
4. Et voilà !

The acf/settings/save_json allows you to change the export directory (default acf-json) but also to auto export groups when a change is made. Very useful for versionning fields structure and settings.

Credits:
https://www.awesomeacf.com/snippets/convert-an-acf-field-group-from-php-to-json/
But the code didn't worked with subfields: repeater/flexible...

Fix by: @justinkmotion
found in: https://gist.github.com/jessepearson/a537b2f78556cd705947