Having a similar issue as http://support.advancedcustomfields.com/forums/topic/get_fields-breaking-after-upgrade-to-acf-pro-on-repeater-field/
As part of a hook to user_register, a custom post type, with an ACF field of type number (no repeaters), is being loaded.
get_field(‘field_name’, post_id)
I have tried changing field type, and giving field key instead. Same result.
Error:
Warning: strpos() expects parameter 1 to be string, array given in wp-content\plugins\advanced-custom-fields\core\api.php on line 40
Call Stack
# Time Memory Function Location
1 0.0024 689784 {main}( ) ..\wp-login.php:0
2 0.4116 43876840 register_new_user( ) ..\wp-login.php:685
3 0.4153 43876872 wp_create_user( ) ..\user.php:2177
4 0.4153 43877832 wp_insert_user( ) ..\user.php:1964
5 0.4692 43967336 do_action( ) ..\user.php:1867
6 0.4692 43968296 call_user_func_array:{wp-includes\plugin.php:505} ( ) ..\plugin.php:505
7 0.4693 43968312 pluginname_registration_save( ) ..\plugin.php:505
8 0.5371 44005624 get_field( ) ..\users.php:121
9 0.5371 44005952 get_field_object( ) ..\api.php:214
10 0.5371 44006784 get_field_reference( ) ..\api.php:271
11 0.5372 44006976 strpos ( ) ..\api.php:40
Version of WP: 4.0
Version of ACF: 4.3.9