I took over a SharePoint site that has customized code to display a list. About two weeks ago, I changed all the groups from "Edit, Contribute, Read, and Approve" permissions to "Contribute" because I felt that it was too much permissions for a users. Well users started to get the
"You do not have the Add and Customize Page permissions, which is required to edit the contents of this web part."
error and they were not able to view the list. I put the "Edit, Contribute, Read, and Approve" back and all is well. Today, the error returned: users no longer able to view the list and they receive the "You do not have the Add and Customize Page permissions..." again.
Is this a web part issue? The web part is a content editor that is linked to a text file with JavaScript code.