Solved: DFS error “The replication group is invalid”

Recently, 1 of my DFS replication groups stopped working with the following error:

Event Type:    Error
Event Source:    DFSR
Event Category:    None
Event ID:    4004
Date:        14/04/2010
Time:        12:55:33
User:        N/A
Computer:    CCK5
Description:
The DFS Replication service stopped replication on the replicated folder at local path D:\DFS Targets\Legacy.

Additional Information:
Error: 9003 (The replication group is invalid)
Additional context of the error: D:\DFS Targets\Legacy\
Replicated Folder Name: Legacy
Replicated Folder ID: B7384F60-E4B2-4686-BB69-B9BD93CF8398
Replication Group Name: villas.cck\dfs\legacy
Replication Group ID: 50A2B981-6B8E-43DD-9D53-B6DE3EC091E4
Member ID: 361EF048-BD7D-449C-A37D-657160F87FC5

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

A google search seemed to indicate that my DFS database had got corrupted on this particular server. Looking in “D:\System Volume Information\DFSR\database_300C_6040_C5F_FEEA” [1] I could see a file called $db_dirty$ whereas the other DFS server had a file called $db_clean$ so I was confident that I’d tracked down the problem.

After making sure I had all data backed up, I stopped the Distributed File System and DFS Replication services, moved the database_300C_6040_C5F_FEEA folder to the desktop then restarted the 2 services. The DFS service then re-built the database and replication started again.

Before doing this, I suggest reading through this article which talks about minimising the effect of re-initialising a DFS member

Foot notes

1 – To get access to the System Volume Information folder, you may need to edit the folder’s security settings to give your login permissions.