Scenario is this - site collection contains a sub-site with unique permissions. In that sub-site, site owner with full control creates link list. That list is not created with the same permissions as the sub-site (appears to have same permissions as site collection root site).
Sub-site owner has read permissions at root site level and consequently cannot add items to newly created link list. Sub-site owner goes to link list permissions and clicks inherit permissions.
Sharepoint gives unexpected error. Entire site collection now locking out all users with 500 internal server error. Central admin unable to do anything with site collection. PowerShell commands do not work on site collection.
Only way to do anything with the site collection was to restore from backup. Restored DB had additional row in the Perms table - suggests the inherit permissions operation may have deleted a row (could explain site collection lockout?).
AFAIK Sharepoint Server and Sql server are fine (space / permissions). Other site collections are operating fine.
Other than not to touch the inherit permissions button, can anyone shed any light on the issue? The issue is repeatable (in different site collections). Site underwent a SP 2007 > 2010 in place migration.