Undefined Error when creating or editing field in Studio

I get an undefined message box pop-up when I create a custom field or edit an existing field. The create/edit works fine. From other posts I have read there are suggestions that this is permissions issue in the Cache Folder. A screen shot of the sub-folders in the Cache directory is attached.

This relates to Version 7.4.3
Sugar Version 6.5.20 (Build 1001)

Any thoughts please ? Thanks.