Cannot access customer page

Hello,

I'm the only administrator and I cannot access "customer/customer", "customer/customer groups",
customer/custom fields" page. The error message is "You do not have permission to access this page, please refer to your system administrator"

I check on "system/user/user groups" all access permission was selected. However, permission listing do not list permission for "customer/customer", "customer/customer groups", "customer/custom fields".

Someone suggest me to replace json with the one from master branch. How do I replace them?

sure it does, exept for the:
customer/custom fields and customer/customer groups
at least in my OC 2 Version, such seems to be called:
customer/customer_group
customer/custom_field

So, probably less an OC-BUG, more just some selfmade Error.
Ernie