0x800706BE

Fixing Server Manager Error 0x800706BE: The Missing MUM/CAT Mystery | Lazy Admin Blog

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If your Server Manager is blank, showing a yellow bang, or refusing to refresh with a “Remote Procedure Call Failed” error, you aren’t looking at a network issue—you’re looking at a corrupted Windows Update store.

When Windows cannot validate the files in the C:\Windows\Servicing\Packages directory, the Server Manager discovery process crashes. Here is how to perform manual surgery on the CBS store to fix it.

The Symptom

  • Error Code: 0x800706BE
  • Event ID: 1601 (Microsoft-Windows-ServerManager/Operational)
  • Message: Could not discover the state of the system.

Step 1: The Diagnostics (CheckSUR)

First, we need to know exactly which files are broken.

  1. Download and run the System Update Readiness Tool (CheckSUR) (KB947821) or, on newer versions of Windows Server, run: DISM.exe /Online /Cleanup-image /Scanhealth
  2. Once finished, open the log file: %Systemroot%\Logs\CBS\Checksur.log
  3. Look for lines starting with (f) CBS MUM Corrupt or (f) CBS MUM Missing. These are your “targets.”

Step 2: Gain Control of the Packages Folder

By default, even an Administrator cannot write to the Servicing folder. You must take ownership:

DOS

takeown /F C:\Windows\Servicing\Packages /D y /R
icacls C:\Windows\Servicing\Packages /save %temp%\AclFile /T
icacls C:\Windows\Servicing\Packages /grant %username%:F /T

Step 3: Extract and Replace the “Grafts”

Now you need to “borrow” healthy files from the original Update files to replace your corrupt ones.

  1. Download the KB: Download the .msu file for the KB number listed as corrupt in your log.
  2. Expand the MSU: expand -F:* Windows6.1-KB978601-x64.msu C:\Repair
  3. Expand the CAB: Inside that folder, find the .cab file and expand it too: expand -F:* Windows6.1-KB978601-x64.cab C:\Repair\CAB
  4. The Extraction: Inside the CAB folder, find update.mum and update.cat.

Step 4: The Rename and Replace

This is where precision matters. You must rename those generic files to match the exact long string found in your Checksur.log.

  • Example Rename:
    • From: update.mum
    • To: Package_for_KB978601~31bf3856ad364e35~amd64~~6.0.1.0.mum
  • Move: Copy these renamed files into C:\Windows\Servicing\Packages.

Step 5: Verify the Fix

Close and reopen Server Manager. It should now trigger a fresh discovery without the RPC error. If it still fails, check the Checksur.log again—you likely have more missing packages to replace!

Lazy Admin Tip 💡

If you have another server running the exact same OS and patch level, you can often just copy the healthy .mum and .cat files from the “Good” server’s C:\Windows\Servicing\Packages folder to the “Bad” one. It’s much faster than manually expanding CAB files!

#WindowsServer #SysAdmin #ServerManager #Troubleshooting #ITOps #Microsoft #TechSupport #LazyAdmin #WindowsUpdate

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