QUESTION:
I tried to merge Contacts from a DupeBlocker Warning but it keeps failing with the following error: INSUFFICIENT_ACCESS_OR_READONLY, cannot merge with entity that is not accessible: How can I resolve?
ANSWER:
That error will occur when both Contacts are enabled as Self Service Users. Salesforce does not allow deletion of a Contact when self-service is enabled. If both contacts have self-service enabled the self-service CANNOT be transferred to the non-master and as a result it will attempt to delete a contact with self-service enabled at the end of the merge and the merge will fail.
This is by design because Salesforce does not allow orgs to ever delete any type of user, regular users or Self-Service users. Just as regular users cannot be deleted because they may be the owner of a record, or the author of a case comment, Self-Service users cannot be deleted because they may be the author of a case comment. This is something Salesforce enforces at the system level, regardless of whether or not that specific Self-Service user has ever authored a case comment.
WORKAROUND:
Before merging contacts that both have active Self-Service usernames, deactivate one Self-Service username. The merged record will adopt the active Self-Service username.