I’m not sure this has to do with ACF plugin but I do got two problems with a front end form file upload field. After the upload I always got an error:
An error occurred in the upload. Please try again later
So I changed the user role capability’s and figured out that the ‘Manage Options’ capability has to be checked, otherwise it won’t upload. As you understand I cannot give normal users this permission.
The second problem is that my field library is set to ‘Uploaded to post’. This works only if I have UNchecked the ‘upload_files’ permission..As soon as I check this option, I can see all uploaded files/images in the library.
BTW I’m using the ‘Members’ plugin to control the capabilty’s. Do you have any idea what might cause these problems and how to solve them?
For a user to upload an image, they need more permissions than just ‘upload_files’.
They also need to be able to edit and add pages and posts. There are some good google discussions regarding this as it effect other plugins as well as ACF.
Perhaps you should test the form with an admin user to avoid the variables of this issue. Does the field library setting work correctly for the admin?