Symptoms

1. Deleting attachments fail with the following error in the browser:

   You are not permitted to perform this operation
   

   OR below in Confluence 2.10 or earlier:

   You cannot view this page due to inherited restrictions.
   
   Page level restrictions have been applied to a parent of the current page. These restrictions limit access to only certain certain user(s) or group(s) and apply to all pages in the hierarchy underneath the parent.
   

2. The following also appears in the atlassian-confluence.log:

   Cause
   java.lang.NullPointerException
   at com.atlassian.confluence.pages.actions.MoveAttachmentAction.bootstrap(MoveAttachmentAction.java:120)
   
   Stack Trace:[hide]
   java.lang.NullPointerException
          at com.atlassian.confluence.pages.actions.MoveAttachmentAction.bootstrap(MoveAttachmentAction.java:120)
          at com.atlassian.confluence.pages.actions.PageAwareInterceptor.intercept(PageAwareInterceptor.java:98)
   

Cause

The issue occurs when the URI encoding hasn't been configured to UTF-8.

There have been isolated reports of this issue occurring on select attachments which are not using any special characters in their file name and the application URI encoding has been set to UTF-8.  Please see the alternative causes article under the resolution section.

Resolution

1. Set the URI Encoding to UTF-8 as per Application Server URL encoding then delete the unwanted attachment afterward.
2. Upgrade to Confluence 3.1. or later, as described in CONF-13671.

See also You Cannot View This Page Due to Inherited Restrictions for alternative causes.