Ah yes - that one's a classic Exchange/AD migration ghost. What you're seeing is an orphaned reference to a deleted Public Folder database, still hanging around in the AD configuration container.

The Problem

You're getting:

Object ... Property [PublicFolderDatabase] is set to value [...] Deleted Objects [...] This property should be fixed as soon as possible.

This means that some mailbox databases (or other Exchange objects) still have a reference to a Public Folder database that was deleted, and AD is now pointing to it in the Deleted Objects container.

This is a harmless but noisy issue - until you try something that expects a clean AD config, such as:

• Installing a new CU
• Adding/removing mailbox databases
• Migrating to modern public folders
• Decommissioning the last 2013 server

What To Do: Clean the Orphaned PublicFolderDatabase Property

You need to clear that attribute manually in AD using ADSIEDIT.

Step-by-Step Fix (ADSIEDIT)

Be cautious in ADSIEDIT - changes are instant and permanent.

1. Open ADSI Edit

• Run adsiedit.msc
• Connect to Configuration context

2. Navigate to the Mailbox Database object

Go to:

CN=Configuration [DC...]
 CN=Services
     CN=Microsoft Exchange
         CN=Argofield HQ
             CN=Administrative Groups
                 CN=Exchange Administrative Group (FYDIBOHF23SPDLT)
                     CN=Databases
                         CN=Mailbox Database 0655979533

3. Right-click Properties

• Find the attribute: msExchHomePublicMDB

• You'll likely see it set to something like:

  CN=Public Folders\0ADEL:34584a90-efcc-4f9d-a2db-16cb21312559,CN=Deleted Objects,...
  

4. Clear it

• Select the attribute
• Click Clear
• Click OK to apply

5. Close ADSIEDIT and wait for replication

This removes the broken reference to the old PF database.

Optional: Check All Databases

You can scan all mailbox databases for stale PF links via PowerShell:

Get-MailboxDatabase | Select Name,PublicFolderDatabase

If any of them are populated, you can clear them with:

Set-MailboxDatabase "Mailbox Database 0655979533" -PublicFolderDatabase $null

Note: This only works if PublicFolderDatabase was still valid in Exchange - if it's already pointing to a deleted object, you must use ADSIEDIT.

Summary

Let me know if you want a script to scan for and report on all such broken PF links across all databases.